## AsciiDoc User Guide

### Stuart Rackham

`<srackham@gmail.com>`

Revision History
Revision 8.4.4 | 26 April 2009 | SJR

AsciiDoc is a text document format for writing documentation, articles, manuals, books and UNIX man pages. AsciiDoc files can be translated to HTML and DocBook markups using the `asciidoc(1)` command. AsciiDoc is highly configurable: both the AsciiDoc source file syntax and the backend output markups (which can be almost any type of SGML/XML markup) can be customized and extended by the user.

## 1. Introduction

Plain text is the most universal electronic document format, no matter what computing environment you use, you can always read and write plain text documentation. But for many applications plain text is not a viable presentation format. HTML, PDF and roff (roff is used for man pages) are the most widely used UNIX presentation formats. DocBook is a popular UNIX documentation markup format which can be translated to HTML, PDF and other presentation formats.

AsciiDoc is a plain text human readable/writable document format that can be translated to DocBook or HTML using the `asciidoc(1)` command. You can then either use `asciidoc(1)` generated HTML directly or run `asciidoc(1)` DocBook output through your favorite DocBook toolchain or use the AsciiDoc `a2x(1)` toolchain wrapper to produce PDF, DVI, LaTeX, PostScript, man page, HTML and text formats.

The AsciiDoc format is a useful presentation format in its own right: AsciiDoc files are unencumbered by markup and are easily viewed, proofed and edited.

AsciiDoc is light weight: it consists of a single Python script and a bunch of configuration files. Apart from `asciidoc(1)` and a Python interpreter, no other programs are required to convert AsciiDoc text files to DocBook or HTML. See Example AsciiDoc Documents below.

You write an AsciiDoc document the same way you would write a normal text document, there are no markup tags or arcane notations. Built-in AsciiDoc formatting rules have been kept to a minimum and are reasonably obvious.

Text markup conventions tend to be a matter of (often strong) personal preference: if the default syntax is not to your liking you can define your own by editing the text based `asciidoc(1)` configuration files. You can create your own configuration files to translate AsciiDoc documents to almost any SGML/XML markup.

`asciidoc(1)` comes with a set of configuration files to translate AsciiDoc articles, books or man pages to HTML or DocBook backend formats.

## 2. Getting Started

### 2.1. Installing AsciiDoc

See the `README` and `INSTALL` files for install prerequisites and procedures. Packagers take a look at Appendix B: Packager Notes.

### 2.2. Example AsciiDoc Documents

The best way to quickly get a feel for AsciiDoc is to view the AsciiDoc web site and/or distributed examples:

- Take a look at the linked examples on the AsciiDoc web site home page http://www.methods.co.nz/asciidoc/. Press the Page Source sidebar menu item to view corresponding AsciiDoc source.
- Read the `.txt` source files in the distribution `./doc` directory in conjunction with the corresponding HTML and DocBook XML files.

## 3. AsciiDoc Document Types

There are three types of AsciiDoc documents: article, book and manpage. All document types share the same AsciiDoc format with some minor variations.

Use the `asciidoc(1)` `-d` (`--doctype`) option to specify the AsciiDoc document type — the default document type is article.

By convention the `.txt` file extension is used for AsciiDoc document source files.

### 3.1. article

Used for short documents, articles and general documentation. See the AsciiDoc distribution `./doc/article.txt` example.

### 3.2. book

Books share the same format as articles; in addition there is the option to add level 0 book part sections.

Book documents will normally be used to produce DocBook output since DocBook processors can automatically generate footnotes, table of contents, list of tables, list of figures, list of examples and indexes.

AsciiDoc markup supports standard DocBook frontmatter and backmatter special sections (dedication, preface, bibliography, glossary, index, colophon) plus footnotes and index entries.

Example book documents

Book
  The `./doc/book.txt` file in the AsciiDoc distribution.
Multi-part book
  The `./doc/book-multi.txt` file in the AsciiDoc distribution.

### 3.3. manpage

Used to generate UNIX manual pages. AsciiDoc manpage documents observe special header title and section naming conventions — see the Manpage Documents section for details.

See also the `asciidoc(1)` man page source (`./doc/asciidoc.1.txt`) from the AsciiDoc distribution.

## 4. AsciiDoc Backends

The `asciidoc(1)` command translates an AsciiDoc formatted file to the backend format specified by the `-b` (`--backend`) command-line option. `asciidoc(1)` itself has little intrinsic knowledge of backend formats, all translation rules are contained in customizable cascading configuration files.

AsciiDoc ships with the following predefined backend output formats:

### 4.1. docbook

AsciiDoc generates the following DocBook document types: article, book and refentry (corresponding to the AsciiDoc article, book and manpage document types).

DocBook documents are not designed to be viewed directly. Most Linux distributions come with conversion tools (collectively called a toolchain) for converting DocBook files to presentation formats such as Postscript, HTML, PDF, DVI, PostScript, LaTeX, roff (the native man page format), HTMLHelp, JavaHelp and text.

- The `--backend=docbook` command-line option produces DocBook XML. You can produce the older DocBook SGML format using the `--attribute sgml` command-line option.
- Use the optional `encoding` attribute to set the character set encoding.
- Use the optional `imagesdir` attribute to prepend to the target file name paths in image inline and block macros. Defaults to a blank string.
- The AsciiDoc Preamble element generates a DocBook book preface element although it’s more usual to use an explicit Preface special section (see the `./doc/book.txt` example book).

### 4.2. xhtml11

The default `asciidoc(1)` backend is `xhtml11` which generates XHTML 1.1 markup styled with CSS2. Default output file have a `.html` extension. xhtml11 document generation is influenced by the following optional attributes (the default behavior is to generate XHTML with no section numbers, embedded CSS and no linked admonition icon images):

numbered
  Adds section numbers to section titles.
toc

  Adds a table of contents to the start of the document.

  - JavaScript needs to be enabled in your browser for this to work.
  - By default AsciiDoc automatically embeds the required `toc.js` JavaScript in the output document — use the linkcss attribute to link the script.

  - The following example generates a numbered table of contents by embedding the `toc.js` script in the `mydoc.html` output document (to link the script to the output document use the linkcss and scriptsdir attributes):

        $ asciidoc -a toc -a numbered mydoc.txt

  - The `toc` attribute must be specified using the `--attribute` command-line option. If you define the `toc` attribute in a custom configuration file it won’t be recognized because the conditionally included header code will have already been processed.
toclevels

  Sets the number of title levels (1..4) reported in the table of contents (see the toc attribute above). Defaults to 2 and must be used with the toc attribute. Example usage:

      $ asciidoc -a toc -a toclevels=3 doc/asciidoc.txt

toc_title
  Sets the table of contents title (defaults to Table of Contents).
linkcss
  Link CSS stylesheets and JavaScripts (see the stylesdir and scriptsdir attributes below). By default linkcss is undefined in which case stylesheets and scripts are automatically embedded in the output document.
scriptsdir
  The name of the directory containing linked JavaScripts. Defaults to `.` (the same directory as the linking document).
stylesdir
  The name of the directory containing linked stylesheets. Defaults to `.` (the same directory as the linking document).
stylesheet
  The file name of an optional additional CSS stylesheet. If you are embedding the stylesheet specify the actual file name; if you are linking CSS specify the file name relative to the directory specified by the stylesdir attribute.
icons
  Link admonition paragraph and admonition block icon images and badge images. By default icons is undefined and text is used in place of icon images.
iconsdir
  The name of the directory containing linked admonition and navigation icons. Defaults to `./images/icons`.
imagesdir
  This attribute is prepended to the target image file name paths in image inline and block macros. Defaults to a blank string.
theme
  Use alternative stylesheets (see Stylesheets).
badges
  Link badges (XHTML 1.1, CSS and Get Firefox!) in document footers. By default badges are omitted (badges is undefined).

The path names of images, icons and scripts are relative to the output document not the source document.

encoding

  Set the input and output document character set encoding. For example the `--attribute encoding=ISO-8859-1` command-line option will set the character set encoding to `ISO-8859-1`.

  - The default encoding is UTF-8.
  - This attribute specifies the character set in the output document.
  - The encoding name must correspond to a Python codec name or alias.

  - The encoding attribute can be set using an AttributeEntry inside the document header but it must come at the start of the document before the document title. For example:

        :encoding: ISO-8859-1

quirks
  Use the `xhtml11-quirks.css` stylesheet to work around IE6 browser incompatibilities (this is the default behavior).
data-uri
  Embed images referenced by image macros using the data: uri scheme.

#### 4.2.1. Stylesheets

AsciiDoc XHTML output is styled using CSS2 stylesheets from the distribution `./stylesheets/` directory.

All browsers have CSS quirks, but Microsoft’s IE6 has so many omissions and errors that the `xhtml11-quirks.css` stylesheet and `xhtml11-quirks.conf` configuration files are included during XHTML backend processing to to implement workarounds for IE6. If you don’t use IE6 then the quirks stylesheet and configuration files can be omitted using the `--attribute quirks!` command-line option.

Default xhtml11 stylesheets:

`./stylesheets/xhtml11.css`
  The main stylesheet.
`./stylesheets/xhtml11-manpage.css`
  Tweaks for manpage document type generation.
`./stylesheets/xhtml11-quirks.css`
  Stylesheet modifications to work around IE6 browser incompatibilities.

Use the theme attribute to select an alternative set of stylesheets. For example, the command-line option `-a theme=foo` will use stylesheets `foo.css`, `foo-manpage.css` and `foo-quirks.css` instead of the default stylesheets.

Use the stylesheet attribute to include an additional stylesheet in XHTML documents. For example, the command-line option `-a stylesheet=newsletter.css` will use stylesheets `newsletter.css`.

### 4.3. html4

This backend generates plain (unstyled) HTML 4.01 Transitional markup.

## 5. Document Structure

An AsciiDoc document consists of a series of block elements starting with an optional document Header, followed by an optional Preamble, followed by zero or more document Sections.

Almost any combination of zero or more elements constitutes a valid AsciiDoc document: documents can range from a single sentence to a multi-part book.

### 5.1. Block Elements

Block elements consist of one or more lines of text and may contain other block elements.

The AsciiDoc block structure can be informally summarized [1] as follows:

    Document      ::= (Header?,Preamble?,Section*)
    Header        ::= (Title,(AuthorLine,RevisionLine?)?)
    AuthorLine    ::= (FirstName,(MiddleName?,LastName)?,EmailAddress?)
    RevisionLine  ::= (Revision?,Date)
    Preamble      ::= (SectionBody)
    Section       ::= (Title,SectionBody?,(Section)*)
    SectionBody   ::= ((BlockTitle?,Block)|BlockMacro)+
    Block         ::= (Paragraph|DelimitedBlock|List|Table)
    List          ::= (BulletedList|NumberedList|LabeledList|CalloutList)
    BulletedList  ::= (ListItem)+
    NumberedList  ::= (ListItem)+
    CalloutList   ::= (ListItem)+
    LabeledList   ::= (ListEntry)+
    ListEntry     ::= (ListLabel,ListItem)
    ListLabel     ::= (ListTerm+)
    ListItem      ::= (ItemText,(List|ListParagraph|ListContinuation)*)

Where:

- ? implies zero or one occurrence, + implies one or more occurrences, * implies zero or more occurrences.
- All block elements are separated by line boundaries.
- `BlockId`, `AttributeEntry` and `AttributeList` block elements (not shown) can occur almost anywhere.
- There are a number of document type and backend specific restrictions imposed on the block syntax.
- The following elements cannot contain blank lines: Header, Title, Paragraph, ItemText.
- A ListParagraph is a Paragraph with its listelement option set.
- A ListContinuation is a list continuation element.

### 5.2. Header

The Header is optional but must start on the first line of the document and must begin with a document title. Optional Author and Revision lines immediately follow the title. The header can be preceded by a CommentBlock or comment lines.

The author line contains the author’s name optionally followed by the author’s email address. The author’s name consists of a first name followed by optional middle and last names separated by white space. Multi-word first, middle and last names can be entered in the header author line using the underscore as a word separator. The email address comes last and must be enclosed in angle <> brackets. Author names cannot contain angle <> bracket characters.

The optional document header revision line should immediately follow the author line. The revision line can be one of two formats:

1. An alphanumeric document revision number followed by a date:

   - The revision number and date must be separated by a comma.
   - The revision number is optional but must contain at least one numeric character.
   - Any non-numeric characters preceding the first numeric character will be dropped.
2. An RCS/CSV/SVN $Id$ marker (if an $Id$ revision marker is used the header author line can be omitted).

The document heading is separated from the remainder of the document by one or more blank lines.

Here’s an example AsciiDoc document header:

    Writing Documentation using AsciiDoc
    ====================================
    Stuart Rackham <srackham@gmail.com>
    v2.0, February 2003

You can override or set header parameters by passing revision, data, email, author, authorinitials, firstname and lastname attributes using the `asciidoc(1)` `-a` (`--attribute`) command-line option. For example:

    $ asciidoc -a date=2004/07/27 article.txt

The revision attribute can be an RCS/CSV/SVN $Id$ marker. Attributes can also be added to the header for substitution in the header template with Attribute Entry elements.

### 5.3. Preamble

The Preamble is an optional untitled section body between the document Header and the first Section title.

### 5.4. Sections

AsciiDoc supports five section levels 0 to 4 (although only book documents are allowed to contain level 0 sections). Section levels are delineated by the section titles.

Sections are translated using configuration file markup templates. To determine which configuration file template to use AsciiDoc first searches for special section titles in the `[specialsections]` configuration entries, if not found it uses the `[sect<level>]` template.

The `-n` (`--section-numbers`) command-line option auto-numbers HTML outputs (DocBook line numbering is handled automatically by the DocBook toolchain commands).

Section IDs are auto-generated from section titles if the `sectids` attribute is defined (the default behavior). The primary purpose of this feature is to ensure persistence of table of contents links: missing section IDs are generated dynamically by the JavaScript TOC generator after the page is loaded. This means, for example, that if you go to a bookmarked dynamically generated TOC address the page will load but the browser will ignore the (as yet ungenerated) section ID.

The IDs are generated by the following algorithm:

- Replace all non-alphanumeric title characters with underscores.
- Strip leading or trailing underscores.
- Convert to lowercase.
- Prepend the `idprefix` attribute (so there’s no possibility of name clashes with existing document IDs). Prepend an underscore if the `idprefix` attribute is not defined.
- A numbered suffix (`_2`, `_3` …) is added if a same named auto-generated section ID exists.

For example the title Jim’s House would generate the ID `_jim_s_house`.

#### 5.4.1. Special Sections

In addition to normal sections, documents can contain optional frontmatter and backmatter sections — for example: preface, bibliography, table of contents, index.

The AsciiDoc configuration file `[specialsections]` section specifies special section titles and the corresponding backend markup templates.

`[specialsections]` entries are formatted like:

    <pattern>=<name>

`<pattern>` is a Python regular expression and `<name>` is the name of a configuration file markup template section. If the `<pattern>` matches an AsciiDoc document section title then the backend output is marked up using the `<name>` markup template (instead of the default `sect<level>` section template). The `{title}` attribute value is set to the value of the matched regular expression group named title, if there is no title group `{title}` defaults to the whole of the AsciiDoc section title. If `<name>` is blank then any existing entry with the same `<pattern>` will be deleted.

AsciiDoc comes preconfigured with the following special section titles:

    Preface                    (book documents only)
    Abstract                   (article documents only)
    Dedication                 (book documents only)
    Glossary
    Bibliography|References
    Colophon                   (book documents only)
    Index
    Appendix [A-Z][:.] <title>

### 5.5. Inline Elements

Inline document elements are used to markup character formatting and various types of text substitution. Inline elements and inline element syntax is defined in the `asciidoc(1)` configuration files.

Here is a list of AsciiDoc inline elements in the (default) order in which they are processed:

Special characters
  These character sequences escape special characters used by the backend markup (typically "<", ">", and "&"). See `[specialcharacters]` configuration file sections.
Quotes
  Characters that markup words and phrases; usually for character formatting. See `[quotes]` configuration file sections.
Special Words
  Word or word phrase patterns singled out for markup without the need for further annotation. See `[specialwords]` configuration file sections.
Replacements
  Each Replacement defines a word or word phrase pattern to search for along with corresponding replacement text. See `[replacements]` configuration file sections.
Attributes
  Document attribute names enclosed in braces (attribute references) are replaced by the corresponding attribute value.
Inline Macros
  Inline macros are replaced by the contents of parametrized configuration file sections.

## 6. Document Processing

The AsciiDoc source document is read and processed as follows:

1. The document Header is parsed, header parameter values are substituted into the configuration file `[header]` template section which is then written to the output file.
2. Each document Section is processed and its constituent elements translated to the output file.
3. The configuration file `[footer]` template section is substituted and written to the output file.

When a block element is encountered `asciidoc(1)` determines the type of block by checking in the following order (first to last): (section) Titles, BlockMacros, Lists, DelimitedBlocks, Tables, AttributeEntrys, AttributeLists, BlockTitles, Paragraphs.

The default paragraph definition `[paradef-default]` is last element to be checked.

Knowing the parsing order will help you devise unambiguous macro, list and block syntax rules.

Inline substitutions within block elements are performed in the following default order:

1. Special characters
2. Quotes
3. Special words
4. Replacements
5. Attributes
6. Inline Macros
7. Replacements2

The substitutions and substitution order performed on Title, Paragraph and DelimitedBlock elements is determined by configuration file parameters.

## 7. Text Formatting

### 7.1. Quoted Text

Words and phrases can be formatted by enclosing inline text with quote characters:

Emphasized text
  Word phrases 'enclosed in single quote characters' (acute accents) or _underline characters_ are emphasized.
Strong text
  Word phrases *enclosed in asterisk characters* are rendered in a strong font (usually bold).
`Monospaced text`
  Word phrases +enclosed in plus characters+ are rendered in a monospaced font. Word phrases `enclosed in backtick characters` (grave accents) are also rendered in a monospaced font but in this case the enclosed text is rendered literally and is not subject to further expansion (see inline literal).
‘Single quoted text’
  Phrases enclosed with a `single grave accent to the left and a single acute accent to the right' are rendered in single quotation marks.
“Double quoted text”
  Phrases enclosed with ``two grave accents to the left and two acute accents to the right'' are rendered in quotation marks.
Unquoted text
  Placing #hashes around text# does nothing, it is a mechanism to allow inline attributes to be applied to otherwise unformatted text (see example below).

Quoted text can be prefixed with an attribute list. Currently the only use made of this feature is to allow the font color, background color and size to be specified (XHTML/HTML only, not DocBook) using the first three positional attribute arguments. The first argument is the text color; the second the background color; the third is the font size. Colors are valid CSS colors and the font size is a number which treated as em units. Here are some examples:

    [red]#Red text#.
    [,yellow]*bold text on a yellow background*.
    [blue,#b0e0e6]+Monospaced blue text on a light blue background+
    [,,2]#Double sized text#.

New quotes can be defined by editing `asciidoc(1)` configuration files. See the Configuration Files section for details.

Quoted text behavior

- Quoting cannot be overlapped.
- Different quoting types can be nested.
- To suppress quoted text formatting place a backslash character immediately in front of the leading quote character(s). In the case of ambiguity between escaped and non-escaped text you will need to escape both leading and trailing quotes, in the case of multi-character quotes you may even need to escape individual characters.
- A configuration file `[quotes]` entry can be subsequently undefined by setting it to a blank value.

#### 7.1.1. Constrained and Unconstrained Quotes

There are actually two types of quotes:

##### 7.1.1.1. Constrained quotes

Quote text that must be bounded by white space, for example a phrase or a word. These are the most common type of quote and are the ones discussed previously.

##### 7.1.1.2. Unconstrained quotes

Unconstrained quotes have no boundary constraints and can be placed anywhere within inline text. For consistency and to make them easier to remember unconstrained quotes are double-ups of the `_`, `*`, `+` and `#` constrained quotes:

    __unconstrained emphasized text__
    **unconstrained strong text**
    ++unconstrained monospaced text++
    ##unconstrained unquoted text##

The following example emboldens the letter F:

    **F**ile Open...

The `__`, `**`, `++` and `##` unconstrained quotes have to be double-escaped (because of their similarity to the single character constrained quotes) — here’s how to escape the previous example:
    \*\*F**ile Open...

### 7.2. Superscripts and Subscripts

Put ^carets on either^ side of the text to be superscripted, put ~tildes on either side~ of text to be subscripted. For example, the following line:

    e^&#960;i^+1 = 0. H~2~O and x^10^. Some ^super text^
    and ~some sub text~

Is rendered like:

eπi+1 = 0. H2O and x10. Some super text and some sub text

Superscripts and subscripts are implemented as unconstrained quotes so they can be escaped with a leading backslash and prefixed with with an attribute list.

### 7.3. Line Breaks

A plus character preceded by at least one space character at the end of a non-blank line forces a line break. It generates a line break (`br`) tag for HTML outputs and a custom XML `asciidoc-br` processing instruction for DocBook outputs. The `asciidoc-br` processing instruction is handled by `a2x(1)` if you use FOP.

### 7.4. Page Breaks

A line of three or more less-than (`<<<`) characters will generate a hard page break in DocBook and printed HTML outputs. It uses the CSS `page-break-after` property for HTML outputs and a custom XML `asciidoc-pagebreak` processing instruction for DocBook outputs. The `asciidoc-pagebreak` processing instruction is handled by `a2x(1)` if you use FOP. Hard page breaks are sometimes handy but as a general rule you should let your page processor generate page breaks for you.

### 7.5. Rulers

A line of three or more apostrophe characters will generate a ruler line. It generates a ruler (`hr`) tag for HTML outputs and a custom XML `asciidoc-hr` processing instruction for DocBook outputs. The `asciidoc-hr` processing instruction is handled by `a2x(1)` if you use FOP.

### 7.6. Tabs

By default tab characters input files will translated to 8 spaces. Tab expansion is set with the tabsize entry in the configuration file `[miscellaneous]` section and can be overridden in included files by setting a tabsize attribute in the `include` macro’s attribute list. For example:

    include::addendum.txt[tabsize=2]

The tab size can also be set using the attribute command-line option, for example `--attribute tabsize=4`

### 7.7. Replacements

The following replacements are defined in the default AsciiDoc configuration:

    (C) copyright, (TM) trademark, (R) registered trademark,
    -- em dash, ... ellipsis, -> right arrow, <- left arrow, => right
    double arrow, <= left double arrow.

Which are rendered as:

© copyright, ™ trademark, ® registered trademark, — em dash, … ellipsis, → right arrow, ← left arrow, ⇒ right double arrow, ⇐ left double arrow.

You can also include arbitrary entity references in the AsciiDoc source. Examples:

    &#x278a; &#182;

renders:

➊ ¶

To render a replacement literally escape it with a leading back-slash.

The Configuration Files section explains how to configure your own replacements.

### 7.8. Special Words

Words defined in `[specialwords]` configuration file sections are automatically marked up without having to be explicitly notated.

The Configuration Files section explains how to add and replace special words.

## 8. Titles

Document and section titles can be in either of two formats:

### 8.1. Two line titles

A two line title consists of a title line, starting hard against the left margin, and an underline. Section underlines consist a repeated character pairs spanning the width of the preceding title (give or take up to three characters):

The default title underlines for each of the document levels are:

    Level 0 (top level):     ======================
    Level 1:                 ----------------------
    Level 2:                 ~~~~~~~~~~~~~~~~~~~~~~
    Level 3:                 ^^^^^^^^^^^^^^^^^^^^^^
    Level 4 (bottom level):  ++++++++++++++++++++++

Examples:

    Level One Section Title
    -----------------------

    Level 2 Subsection Title
    ~~~~~~~~~~~~~~~~~~~~~~~~

### 8.2. One line titles

One line titles consist of a single line delimited on either side by one or more equals characters (the number of equals characters corresponds to the section level minus one). Here are some examples:

    = Document Title (level 0) =
    == Section title (level 1) ==
    === Section title (level 2) ===
    ==== Section title (level 3) ====
    ===== Section title (level 4) =====

Note

- One or more spaces must fall between the title and the delimiters.
- The trailing title delimiter is optional.
- The one-line title syntax can be changed by editing the configuration file `[titles]` section `sect0`…`sect4` entries.

### 8.3. Floating titles

Setting the first title attribute to `float` generates a free-floating title. A free-floating title is rendered just like a normal section title but is not formally associated with a text body and is not part of the regular section hierarchy so the normal ordering rules do not apply. Floating titles can also be used in contexts where section titles are illegal: for example sidebar and admonition blocks. Example:

    [float]
    The second day
    ~~~~~~~~~~~~~~

## 9. Block Titles

A BlockTitle element is a single line beginning with a period followed by the title text. A BlockTitle is applied to the immediately following Paragraph, DelimitedBlock, List, Table or BlockMacro. For example:

    .Notes
    - Note 1.
    - Note 2.

is rendered as:

Notes

- Note 1.
- Note 2.

## 10. BlockId Element

A BlockId is a single line block element containing a unique identifier enclosed in double square brackets. It is used to assign an identifier to the ensuing block element for use by referring links. For example:

    [[chapter-titles]]
    Chapter titles can be ...

The preceding example identifies the following paragraph so it can be linked from other location, for example with `<<chapter-titles,chapter titles>>`.

BlockId elements can be applied to Title, Paragraph, List, DelimitedBlock, Table and BlockMacro elements. The BlockId element sets the `{id}` attribute for substitution in the subsequent block’s markup template. If a second argument is supplied it sets the `{reftext}` attribute which is used to set the DocBook `xreflabel` attribute.

The BlockId element has the same syntax and serves a similar function to the anchor inline macro.

## 11. AttributeList Element

An AttributeList block element is an attribute list on a line by itself. AttributeList attributes are only applied to the following block element — the attributes are available for markup template substitution. Often the first attribute in the list is used to specify the following element’s style.

By default only attribute references are substituted within attribute values, this is because not all attributes are destined to be marked up and rendered as text (for example the table cols attribute). To perform normal inline text substitutions (special characters, quotes, macros, replacements) on an attribute value you need to enclose it in single quotes. In the following quote block the second attribute value in the AttributeList is quoted to ensure the http macro is expanded to a hyperlink.

    [quote,'http://en.wikipedia.org/wiki/Samuel_Johnson[Samuel Johnson]']
    _____________________________________________________________________
    Sir, a woman's preaching is like a dog's walking on his hind legs. It
    is not done well; but you are surprised to find it done at all.
    _____________________________________________________________________

## 12. Paragraphs

Paragraphs are blocks of text terminated by a blank line, the end of file, or the start of a DelimitedBlock. Paragraph markup is specified by configuration file `[paradef*]` sections.

Normal paragraphs consist of one or more non-blank lines of text. The first line must start hard against the left margin (no intervening white space). The default processing expectation is that of a normal paragraph of text. literal and verse paragraph styles are available (in addition to the default paragraph style).

### 12.1. literal paragraph style

Literal paragraphs are rendered verbatim in a monospaced font without any distinguishing background or border. By default there is no text formatting or substitutions within Literal paragraphs apart from Special Characters and Callouts. For example:

    [literal]
    Consul *necessitatibus* per id,
    consetetur, eu pro everti postulant
    homero verear ea mea, qui.

Renders:

    Consul *necessitatibus* per id,
    consetetur, eu pro everti postulant
    homero verear ea mea, qui.

### 12.2. verse paragraph style

The verse paragraph style preserves line boundaries and is useful for lyrics and poems. For example:

    [verse]
    Consul *necessitatibus* per id,
    consetetur, eu pro everti postulant
    homero verear ea mea, qui.

Renders:

> Consul necessitatibus per id,
> consetetur, eu pro everti postulant
> homero verear ea mea, qui.

### 12.3. Indented paragraphs

Indented paragraphs (the first line indented by one or more space or tab characters) are rendered using the literal paragraph style. For example:

      Consul *necessitatibus* per id,
      consetetur, eu pro everti postulant
      homero verear ea mea, qui.

Renders:

    Consul *necessitatibus* per id,
    consetetur, eu pro everti postulant
    homero verear ea mea, qui.

Because lists can be indented it’s possible for your indented paragraph to be misinterpreted as a list — in situations like this apply the literal style to a normal paragraph.

### 12.4. Admonition Paragraphs

Tip, Note, Important, Warning and Caution paragraph definitions support the corresponding DocBook admonishment elements — just write a normal paragraph but place `NOTE:`, `TIP:`, `IMPORTANT:`, `WARNING:` or `CAUTION:` as the first word of the paragraph. For example:

    NOTE: This is an example note.

or the alternative syntax:

    [NOTE]
    This is an example note.

Renders:

This is an example note.

If your admonition is more than a single paragraph use an admonition block instead.

#### 12.4.1. Admonition Icons and Captions

Admonition customization with `icons`, `iconsdir`, `icon` and `caption` attributes does not apply when generating DocBook output. If you are going the DocBook route then the `a2x(1)` `--no-icons` and `--icons-dir` options can be used to set the appropriate XSL Stylesheets parameters.

By default the `asciidoc(1)` `xhtml11` and `html4` backends generate text captions instead of icon image links. To generate links to icon images define the `icons` attribute, for example using the `-a icons` command-line option.

The `iconsdir` attribute sets the location of linked icon images.

You can override the default icon image using the `icon` attribute to specify the path of the linked image. For example:

    [icon="./images/icons/wink.png"]
    NOTE: What lovely war.

Use the `caption` attribute to customize the admonition captions (not applicable to `docbook` backend). The following example suppresses the icon image and customizes the caption of a NOTE admonition (undefining the `icons` attribute with `icons=None` is only necessary if admonition icons have been enabled):

    [icons=None, caption="My Special Note"]
    NOTE: This is my special note.

This subsection also applies to Admonition Blocks.

## 13. Delimited Blocks

Delimited blocks are blocks of text enveloped by leading and trailing delimiter lines (normally a series of four or more repeated characters). The behavior of Delimited Blocks is specified by entries in configuration file `[blockdef*]` sections.

### 13.1. Predefined Delimited Blocks

AsciiDoc ships with a number of predefined DelimitedBlocks (see the `asciidoc.conf` configuration file in the `asciidoc(1)` program directory):

Predefined delimited block underlines:

    CommentBlock:     //////////////////////////
    PassthroughBlock: ++++++++++++++++++++++++++
    ListingBlock:     --------------------------
    LiteralBlock:     ..........................
    SidebarBlock:     **************************
    QuoteBlock:       __________________________
    ExampleBlock:     ==========================
    OpenBlock:        --

The code, source and music filter blocks are detailed in the Filters section.

Table 1. Default DelimitedBlock substitutions

| Attributes | Callouts | Macros | Quotes | Replacements | Special chars | Special words
--- | --- | --- | --- | --- | --- | --- | ---
PassthroughBlock | Yes | No | Yes | No | No | No | No
ListingBlock | No | Yes | No | No | No | Yes | No
LiteralBlock | No | Yes | No | No | No | Yes | No
SidebarBlock | Yes | No | Yes | Yes | Yes | Yes | Yes
QuoteBlock | Yes | No | Yes | Yes | Yes | Yes | Yes
ExampleBlock | Yes | No | Yes | Yes | Yes | Yes | Yes
OpenBlock | Yes | No | Yes | Yes | Yes | Yes | Yes

### 13.2. Listing Blocks

ListingBlocks are rendered verbatim in a monospaced font, they retain line and whitespace formatting and are often distinguished by a background or border. There is no text formatting or substitutions within Listing blocks apart from Special Characters and Callouts. Listing blocks are often used for computer output and file listings.

Here’s an example:

    --------------------------------------
    #include <stdio.h>

    int main() {
       printf("Hello World!\n");
       exit(0);
    }
    --------------------------------------

Which will be rendered like:

    #include <stdio.h>

    int main() {
        printf("Hello World!\n");
        exit(0);
    }

By convention filter blocks use the listing block syntax and are implemented as listing block styles.

### 13.3. Literal Blocks

LiteralBlocks behave just like LiteralParagraphs except you don’t have to indent the contents.

If the listing style is applied to a LiteralBlock it will be rendered as a ListingBlock (this is handy if you have a listing containing a ListingBlock).

    ...................................
    Consul *necessitatibus* per id,
    consetetur, eu pro everti postulant
    homero verear ea mea, qui.
    ...................................

Renders:

    Consul *necessitatibus* per id,
    consetetur, eu pro everti postulant
    homero verear ea mea, qui.

### 13.4. Sidebar Blocks

A sidebar is a short piece of text presented outside the narrative flow of the main text. The sidebar is normally presented inside a bordered box to set it apart from the main text.

The sidebar body is treated like a normal section body.

Here’s an example:

    .An Example Sidebar
    ************************************************
    Any AsciiDoc SectionBody element (apart from
    SidebarBlocks) can be placed inside a sidebar.
    ************************************************

Which will be rendered like:

Apply the abstract style to generate an abstract, for example:

    [abstract]
    ************************************************
    In this paper we will attempt to...
    ************************************************

### 13.5. Comment Blocks

The contents of CommentBlocks are not processed; they are useful for annotations and for excluding new or outdated content that you don’t want displayed. CommentBlocks are never written to output files. Example:

    //////////////////////////////////////////
    CommentBlock contents are not processed by
    asciidoc(1).
    //////////////////////////////////////////

See also Comment Lines.

System macros are executed inside comment blocks.

### 13.6. Passthrough Blocks

By default the block contents is subject to attribute and macro substitution, no other markup is generated. PassthroughBlock content will often be backend specific. Here’s an example:

    ++++++++++++++++++++++++++++++++++++++
    <table border="1"><tr>
      <td>Cell 1</td>
      <td>Cell 2</td>
    </tr></table>
    ++++++++++++++++++++++++++++++++++++++

Use and explicit subs attribute to control substitution. The following styles can be applied to passthrough blocks:

pass
  By default no substitutions are performed.
asciimath, latexmath
  By default no substitutions are performed, the contents are rendered as mathematical formulas.

### 13.7. Quote Blocks

QuoteBlocks are used for quoted passages of text. There are two styles: quote and verse. The style is set by the first positional attribute, if no style attribute is specified the quote style. The optional attribution and citetitle attributes (positional attributes 2 and 3) specify the quote’s author and source.

The quote style treats the content like a SectionBody, for example:

    [quote, Bertrand Russell, The World of Mathematics (1956)]
    ____________________________________________________________________
    A good notation has subtlety and suggestiveness which at times makes
    it almost seem like a live teacher.
    ____________________________________________________________________

Which is rendered as:

| A good notation has subtlety and suggestiveness which at times makes it almost seem like a live teacher. |
| -- Bertrand Russell The World of Mathematics (1956)

The verse style retains the content’s line breaks, for example:

    [verse, William Blake, from Auguries of Innocence]
    __________________________________________________
    To see a world in a grain of sand,
    And a heaven in a wild flower,
    Hold infinity in the palm of your hand,
    And eternity in an hour.
    __________________________________________________

Which is rendered as:

| To see a world in a grain of sand, And a heaven in a wild flower, Hold infinity in the palm of your hand, And eternity in an hour. |
| -- William Blake from Auguries of Innocence

### 13.8. Example Blocks

ExampleBlocks encapsulate the DocBook Example element and are used for, well, examples. Example blocks can be titled by preceding them with a BlockTitle. DocBook toolchains normally number examples and generate a List of Examples backmatter section.

Example blocks are delimited by lines of equals characters and you can put any block elements apart from Titles, BlockTitles and Sidebars) inside an example block. For example:

    .An example
    =====================================================================
    Qui in magna commodo, est labitur dolorum an. Est ne magna primis
    adolescens.
    =====================================================================

Renders:

Example 1. An example

Qui in magna commodo, est labitur dolorum an. Est ne magna primis adolescens.

A title prefix that can be inserted with the `caption` attribute (`xhtml11` and `html4` backends). For example:

    [caption="Example 1: "]
    .An example with a custom caption
    =====================================================================
    Qui in magna commodo, est labitur dolorum an. Est ne magna primis
    adolescens.
    =====================================================================

### 13.9. Admonition Blocks

The ExampleBlock definition includes a set of admonition styles (NOTE, TIP, IMPORTANT, WARNING, CAUTION) for generating admonition blocks (admonitions containing more than just a simple paragraph). Just precede the ExampleBlock with an attribute list containing the admonition style name. For example:

    [NOTE]
    .A NOTE block
    =====================================================================
    Qui in magna commodo, est labitur dolorum an. Est ne magna primis
    adolescens.

    . Fusce euismod commodo velit.
    . Vivamus fringilla mi eu lacus.
      .. Fusce euismod commodo velit.
      .. Vivamus fringilla mi eu lacus.
    . Donec eget arcu bibendum
      nunc consequat lobortis.
    =====================================================================

Renders:

| A NOTE block
Qui in magna commodo, est labitur dolorum an. Est ne magna primis adolescens. Fusce euismod commodo velit. Vivamus fringilla mi eu lacus. Fusce euismod commodo velit. Vivamus fringilla mi eu lacus. Donec eget arcu bibendum nunc consequat lobortis.

See also Admonition Icons and Captions.

### 13.10. Open Blocks

An OpenBlock renders the block contents without any opening or closing tags. The open block start and end delimiter is a single line containing two dashes. Enclosed elements are rendered just as they would inside a section body. Open blocks are used for list item continuation.

## 14. Lists

List types

- Bulleted lists. Also known as itemized or unordered lists.
- Numbered lists. Also called ordered lists.
- Labeled lists. Sometimes called variable or definition lists.
- Callout lists (a list of callout annotations).

List behavior

- List item indentation is optional and does not determine nesting, indentation does however make the source more readable.
- Another list or a literal paragraph immediately following a list item will be implicitly included in the list item; use list item continuation to explicitly append other block elements to a list item.
- A comment block or a comment line block macro element will terminate a list — use inline comment lines to put comments inside lists.
- The `listindex` intrinsic attribute is the current list item index (1..). If this attribute is not inside a list then it’s value is the number of items in the most recently closed list. Useful for displaying the number of items in a list.

### 14.1. Bulleted Lists

Bulleted list items start with a single dash or one to five asterisks followed by some white space then some text. Bulleted list syntaxes are:

    - List item.
    * List item.
    ** List item.
    *** List item.
    **** List item.
    ***** List item.

### 14.2. Numbered Lists

List item numbers are explicit or implicit.

Explicit numbering. List items begin with a number followed by some white space then the item text. The numbers can be decimal (arabic), roman (upper or lower case) or alpha (upper or lower case). Decimal and alpha numbers are terminated with a period, roman numbers are terminated with a closing parenthesis. The different terminators are necessary to ensure i, v and x roman numbers are are distinguishable from x, v and x alpha numbers. Examples:

    1.   Arabic (decimal) numbered list item.
    a.   Lower case alpha (letter) numbered list item.
    F.   Upper case alpha (letter) numbered list item.
    iii) Lower case roman numbered list item.
    IX)  Upper case roman numbered list item.

Implicit numbering. List items begin one to five period characters, followed by some white space then the item text. Examples:

    . Arabic (decimal) numbered list item.
    .. Lower case alpha (letter) numbered list item.
    ... Lower case roman numbered list item.
    .... Upper case alpha (letter) numbered list item.
    ..... Upper case roman numbered list item.

You can use the style attribute to specify an alternative numbering style. The numbered list style can be one of the following values: arabic, loweralpha, upperalpha, lowerroman, upperroman.

Here are some examples of bulleted and numbered lists:

    - Praesent eget purus quis magna eleifend eleifend.
      1. Fusce euismod commodo velit.
        a. Fusce euismod commodo velit.
        b. Vivamus fringilla mi eu lacus.
        c. Donec eget arcu bibendum nunc consequat lobortis.
      2. Vivamus fringilla mi eu lacus.
        i)  Fusce euismod commodo velit.
        ii) Vivamus fringilla mi eu lacus.
      3. Donec eget arcu bibendum nunc consequat lobortis.
      4. Nam fermentum mattis ante.
    - Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
      * Fusce euismod commodo velit.
      ** Qui in magna commodo, est labitur dolorum an. Est ne magna primis
         adolescens. Sit munere ponderum dignissim et. Minim luptatum et
         vel.
      ** Vivamus fringilla mi eu lacus.
      * Donec eget arcu bibendum nunc consequat lobortis.
    - Nulla porttitor vulputate libero.
      . Fusce euismod commodo velit.
      . Vivamus fringilla mi eu lacus.
    [upperroman]
        .. Fusce euismod commodo velit.
        .. Vivamus fringilla mi eu lacus.
      . Donec eget arcu bibendum nunc consequat lobortis.

Which render as:

- Praesent eget purus quis magna eleifend eleifend.

  1. Fusce euismod commodo velit.

     1. Fusce euismod commodo velit.
     2. Vivamus fringilla mi eu lacus.
     3. Donec eget arcu bibendum nunc consequat lobortis.

  2. Vivamus fringilla mi eu lacus.

     1. Fusce euismod commodo velit.
     2. Vivamus fringilla mi eu lacus.
  3. Donec eget arcu bibendum nunc consequat lobortis.
  4. Nam fermentum mattis ante.

- Lorem ipsum dolor sit amet, consectetuer adipiscing elit.

  - Fusce euismod commodo velit.

    - Qui in magna commodo, est labitur dolorum an. Est ne magna primis adolescens. Sit munere ponderum dignissim et. Minim luptatum et vel.
    - Vivamus fringilla mi eu lacus.
  - Donec eget arcu bibendum nunc consequat lobortis.

- Nulla porttitor vulputate libero.

  1. Fusce euismod commodo velit.

  2. Vivamus fringilla mi eu lacus.

     1. Fusce euismod commodo velit.
     2. Vivamus fringilla mi eu lacus.
  3. Donec eget arcu bibendum nunc consequat lobortis.

A predefined compact option is available to bulleted and numbered lists — this translates to the DocBook spacing="compact" lists attribute which may or may not be processed by the DocBook toolchain. Example:

    [options="compact"]
    - Compact list item.
    - Another compact list item.

To apply the compact option globally define a document-wide compact-option attribute, e.g. using the `-a compact-option` command-line option.

### 14.3. Labeled Lists

Labeled list items consist of one or more text labels followed the text of the list item.

An item label begins a line with an alphanumeric character hard against the left margin and ends with one to four colons or two semi-colons. A list item can have multiple labels, one per line.

The list item text consists of one or more lines of text starting after the last label (either on the same line or a new line) and can be followed by nested List or ListParagraph elements. Item text can be optionally indented.

Here are some examples:

    In::
    Lorem::
      Fusce euismod commodo velit.

      Fusce euismod commodo velit.

    Ipsum:: Vivamus fringilla mi eu lacus.
      * Vivamus fringilla mi eu lacus.
      * Donec eget arcu bibendum nunc consequat lobortis.
    Dolor::
      Donec eget arcu bibendum nunc consequat lobortis.
      Suspendisse;;
        A massa id sem aliquam auctor.
      Morbi;;
        Pretium nulla vel lorem.
      In;;
        Dictum mauris in urna.
        Vivamus::: Fringilla mi eu lacus.
        Donec:::   Eget arcu bibendum nunc consequat lobortis.

Which render as:

In , Lorem

  Fusce euismod commodo velit.

      Fusce euismod commodo velit.

Ipsum

  Vivamus fringilla mi eu lacus.

  - Vivamus fringilla mi eu lacus.
  - Donec eget arcu bibendum nunc consequat lobortis.
Dolor

  Donec eget arcu bibendum nunc consequat lobortis.

  Suspendisse
    A massa id sem aliquam auctor.
  Morbi
    Pretium nulla vel lorem.
  In

    Dictum mauris in urna.

    Vivamus
      Fringilla mi eu lacus.
    Donec
      Eget arcu bibendum nunc consequat lobortis.

#### 14.3.1. Horizontal labeled list style

The horizontal labeled list style places the list text side-by-side with the label instead of under the label. Here is an example:

    [horizontal]
    *Lorem*:: Fusce euismod commodo velit.  Qui in magna commodo, est
    labitur dolorum an. Est ne magna primis adolescens.

      Fusce euismod commodo velit.

    *Ipsum*:: Vivamus fringilla mi eu lacus.
    - Vivamus fringilla mi eu lacus.
    - Donec eget arcu bibendum nunc consequat lobortis.

    *Dolor*::
      - Vivamus fringilla mi eu lacus.
      - Donec eget arcu bibendum nunc consequat lobortis.

Which render as:

Lorem | Fusce euismod commodo velit. Qui in magna commodo, est labitur dolorum an. Est ne magna primis adolescens.
    Fusce euismod commodo velit.
Ipsum | Vivamus fringilla mi eu lacus. Vivamus fringilla mi eu lacus. Donec eget arcu bibendum nunc consequat lobortis.
Dolor | Vivamus fringilla mi eu lacus. Donec eget arcu bibendum nunc consequat lobortis.

Current PDF toolchains do not make a good job of determining the relative column widths for horizontal labeled lists. If you are generating DocBook markup then horizontal labeled lists should not be nested because the DocBook XML V4.2 DTD does not permit nested informal tables (although DocBook XSL Stylesheets and dblatex process them correctly). The label width can be set as a percentage of the total width by setting the width attribute e.g. `width="10%"`

### 14.4. Question and Answer Lists

AsciiDoc comes pre-configured with a qanda style labeled list for generating DocBook question and answer (Q&A) lists. Example:

    [qanda]
    Question one::
            Answer one.
    Question two::
            Answer two.

Renders:

14.4.1. Question one
14.4.2. Question two

14.4.1. | Question one
| Answer one.
14.4.2. | Question two
| Answer two.

### 14.5. Glossary Lists

AsciiDoc comes pre-configured with a glossary style labeled list for generating DocBook glossary lists. Example:

    [glossary]
    A glossary term::
        The corresponding definition.
    A second glossary term::
        The corresponding definition.

For working examples see the `article.txt` and `book.txt` documents in the AsciiDoc `./doc` distribution directory.

To generate valid DocBook output glossary lists must be located in a glossary section.

### 14.6. Bibliography Lists

AsciiDoc comes with a predefined bibliography bulleted list style generating DocBook bibliography entries. Example:

    [bibliography]
    - [[[taoup]]] Eric Steven Raymond. 'The Art of UNIX
      Programming'. Addison-Wesley. ISBN 0-13-142901-9.
    - [[[walsh-muellner]]] Norman Walsh & Leonard Muellner.
      'DocBook - The Definitive Guide'. O'Reilly & Associates.
      1999. ISBN 1-56592-580-7.

The `[[[<reference>]]]` syntax is a bibliography entry anchor, it generates an anchor named `<reference>` and additionally displays `[<reference>]` at the anchor position. For example `[\[[taoup]]]` generates an anchor named `taoup` that displays `[taoup]` at the anchor position. Cite the reference from elsewhere your document using `<<taoup>>`, this displays a hyperlink (`[taoup]`) to the corresponding bibliography entry anchor.

For working examples see the `article.txt` and `book.txt` documents in the AsciiDoc `./doc` distribution directory.

To generate valid DocBook output bibliography lists must be located in a bibliography section.

### 14.7. List Item Continuation

Another list or a literal paragraph immediately following a list item is implicitly appended to the list item; to append other block elements to a list item you need to explicitly join them to the list item with a list continuation (a separator line containing a single plus character). Multiple block elements can be appended to a list item using list continuations (provided they are legal list item children in the backend markup).

Here are some examples of list item continuations: list item one contains multiple continuations; list item two is continued with an OpenBlock containing multiple elements:

    1. List item one.
    +
    List item one continued with a second paragraph followed by an
    Indented block.
    +
    .................
    $ ls *.sh
    $ mv *.sh ~/tmp
    .................
    +
    List item continued with a third paragraph.

    2. List item two continued with an open block.
    +
    --
    This paragraph is part of the preceding list item.

    a. This list is nested and does not require explicit item continuation.
    +
    This paragraph is part of the preceding list item.

    b. List item b.

    This paragraph belongs to item two of the outer list.
    --

Renders:

1. List item one.

   List item one continued with a second paragraph followed by an Indented block.

       $ ls *.sh
       $ mv *.sh ~/tmp

   List item continued with a third paragraph.

2. List item two continued with an open block.

   This paragraph is part of the preceding list item.

   1. This list is nested and does not require explicit item continuation.

      This paragraph is part of the preceding list item.

   2. List item b.

   This paragraph belongs to item two of the outer list.

## 15. Footnotes

The shipped AsciiDoc configuration includes the `footnote:[<text>]` and `footnoteref:[<id>,<text>]` inline macros for generating footnotes:

- The `footnote` macro generates a footnote.
- The `footnoteref` macro has two forms: if the text is supplied a foot note with an ID is generated; if the text is omitted a reference to the footnote with the specified ID is generated.
- The footnote text can span multiple lines.

Example footnote:

    A footnote footnote:[An example footnote.];
    a second footnote with a reference ID footnoteref:[note2,Second footnote.];
    finally a reference to the second footnote footnoteref:[note2].

Which renders:

A footnote [2]; a second footnote with a reference ID [3]; finally a reference to the second footnote [3].

Footnotes are primarily useful when generating DocBook output — DocBook conversion programs render footnote outside the primary text flow.

## 16. Indexes

The shipped AsciiDoc configuration includes the inline macros for generating document index entries.

`indexterm:[<primary>,<secondary>,<tertiary>]` , `(((<primary>,<secondary>,<tertiary>)))`
  This inline macro generates an index term (the <secondary> and <tertiary> attributes are optional). For example `indexterm:[Tigers,Big cats]` (or, using the alternative syntax `(((Tigers,Big cats)))`. Index terms that have secondary and tertiary entries also generate separate index terms for the secondary and tertiary entries. The index terms appear in the index, not the primary text flow.
`indexterm2:[<primary>]` , `((<primary>))`
  This inline macro generates an index term that appears in both the index and the primary text flow. The `<primary>` should not be padded to the left or right with white space characters.

For working examples see the `article.txt` and `book.txt` documents in the AsciiDoc `./doc` distribution directory.

Index entries only really make sense if you are generating DocBook markup — DocBook conversion programs automatically generate an index at the point an Index section appears in source document.

## 17. Callouts

Callouts are a mechanism for annotating verbatim text (source code, computer output and user input for example). Callout markers are placed inside the annotated text while the actual annotations are presented in a callout list after the annotated text. Here’s an example:

     .MS-DOS directory listing
     -----------------------------------------------------
     10/17/97   9:04         <DIR>    bin
     10/16/97  14:11         <DIR>    DOS            <1>
     10/16/97  14:40         <DIR>    Program Files
     10/16/97  14:46         <DIR>    TEMP
     10/17/97   9:04         <DIR>    tmp
     10/16/97  14:37         <DIR>    WINNT
     10/16/97  14:25             119  AUTOEXEC.BAT   <2>
      2/13/94   6:21          54,619  COMMAND.COM    <2>
     10/16/97  14:25             115  CONFIG.SYS     <2>
     11/16/97  17:17      61,865,984  pagefile.sys
      2/13/94   6:21           9,349  WINA20.386     <3>
     -----------------------------------------------------

     <1> This directory holds MS-DOS.
     <2> System startup code for DOS.
     <3> Some sort of Windows 3.1 hack.

Which renders:

Example 2. MS-DOS directory listing

    10/17/97   9:04         <DIR>    bin
    10/16/97  14:11         <DIR>    DOS
    10/16/97  14:40         <DIR>    Program Files
    10/16/97  14:46         <DIR>    TEMP
    10/17/97   9:04         <DIR>    tmp
    10/16/97  14:37         <DIR>    WINNT
    10/16/97  14:25             119  AUTOEXEC.BAT
     2/13/94   6:21          54,619  COMMAND.COM
    10/16/97  14:25             115  CONFIG.SYS
    11/16/97  17:17      61,865,984  pagefile.sys
     2/13/94   6:21           9,349  WINA20.386

| This directory holds MS-DOS.
| System startup code for DOS.
| Some sort of Windows 3.1 hack.

Explanation

- The callout marks are whole numbers enclosed in angle brackets that refer to an item index in the following callout list.
- By default callout marks are confined to LiteralParagraphs, LiteralBlocks and ListingBlocks (although this is a configuration file option and can be changed).
- Callout list item numbering is fairly relaxed — list items can start with `<n>`, `n>` or `>` where `n` is the optional list item number (in the latter case list items starting with a single `>` character are implicitly numbered starting at one).
- Callout lists should not be nested — start list items hard against the left margin.
- If you want to present a number inside angle brackets you’ll need to escape it with a backslash to prevent it being interpreted as a callout mark.

To include callout icons in PDF files generated by `a2x(1)` you need to use the `--icons` command-line option.

### 17.1. Implementation Notes

Callout marks are generated by the callout inline macro while callout lists are generated using the callout list definition. The callout macro and callout list are special in that they work together. The callout inline macro is not enabled by the normal macros substitutions option, instead it has its own callouts substitution option.

The following attributes are available during inline callout macro substitution:

`{index}`
  The callout list item index inside the angle brackets.
`{coid}`
  An identifier formatted like `CO<listnumber>-<index>` that uniquely identifies the callout mark. For example `CO2-4` identifies the fourth callout mark in the second set of callout marks.

The `{coids}` attribute can be used during callout list item substitution — it is a space delimited list of callout IDs that refer to the explanatory list item.

### 17.2. Including callouts in included code

You can annotate working code examples with callouts — just remember to put the callouts inside source code comments. This example displays the `test.py` source file (containing a single callout) using the Source Code Highlighter Filter:

Example 3. AsciiDoc source

    [source,python]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    include::test.py[]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    <1> Print statement.

Example 4. Included `test.py` source

    print 'Hello World!'   # <1>

## 18. Macros

Macros are a mechanism for substituting parametrized text into output documents.

Macros have a name, a single target argument and an attribute list. The usual syntax is `<name>:<target>[<attrlist>]` (for inline macros) and `<name>::<target>[<attrlist>]` (for block macros). Here are some examples:

    http://www.methods.co.nz/asciidoc/index.html[Asciidoc home page]
    include::chapt1.txt[tabsize=2]
    mailto:srackham@gmail.com[]

Macro behavior

- `<name>` is the macro name. It can only contain letters, digits or dash characters and cannot start with a dash.
- The optional `<target>` cannot contain white space characters.
- `<attrlist>` is a list of attributes enclosed in square brackets.
- `]` characters in attribute lists that are enclosed in `[]` brackets must be escaped with a backslash.
- Expansion of non-system macro references can normally be escaped by prefixing a backslash character (see the AsciiDoc FAQ for examples of exceptions to this rule).
- System macros cannot be escaped.
- Attribute references in block macros are expanded.
- The substitutions performed prior to Inline macro macro expansion are determined by the inline context.
- Macros are processed in the order they appear in the configuration file(s).
- Calls to inline macros can be nested inside different inline macros (an inline macro call cannot contain a nested call to itself).
- In addition to `<name>`, `<target>` and `<attrlist>` the `<passtext>` and `<subslist>` named groups are available to passthrough macros. A macro is a passthrough macro if the definition includes a `<passtext>` named group.

### 18.1. Inline Macros

Inline Macros occur in an inline element context. Predefined Inline macros include URLs, image and link macros.

#### 18.1.1. URLs

http, https, ftp, file, mailto and callto URLs are rendered using predefined inline macros.

- If you don’t need a customized the link caption you can enter the http, https, ftp, file URLs and email addresses without any special macro syntax.
- If the `<attrlist>` is empty the URL is displayed.

Here are some examples:

    http://www.methods.co.nz/asciidoc/[The AsciiDoc home page]
    http://www.methods.co.nz/asciidoc/
    mailto:joe.bloggs@foobar.com[email Joe Bloggs]
    joe.bloggs@foobar.com
    callto:joe.bloggs[]

Which are rendered:

The AsciiDoc home page

http://www.methods.co.nz/asciidoc/

email Joe Bloggs

joe.bloggs@foobar.com

joe.bloggs

- If the `<target>` necessitates space characters they should be replaced by `%20`. For example `large%20image.png`.
- Define an attribute entry if you refer to the same URL more than once, this will make your document easier to maintain and easier to read.

#### 18.1.2. Internal Cross References

Two AsciiDoc inline macros are provided for creating hypertext links within an AsciiDoc document. You can use either the standard macro syntax or the (preferred) alternative.

##### 18.1.2.1. anchor

Used to specify hypertext link targets:

    [[<id>,<xreflabel>]]
    anchor:<id>[<xreflabel>]

The `<id>` is a unique identifier that must begin with a letter. The optional `<xreflabel>` is the text to be displayed by captionless xref macros that refer to this anchor. The optional `<xreflabel>` is only really useful when generating DocBook output. Example anchor:

    [[X1]]

You may have noticed that the syntax of this inline element is the same as that of the BlockId block element, this is no coincidence since they are functionally equivalent.

##### 18.1.2.2. xref

Creates a hypertext link to a document anchor.

    <<<id>,<caption>>>
    xref:<id>[<caption>]

The `<id>` refers to an existing anchor `<id>`. The optional `<caption>` is the link’s displayed text. Example:

    <<X21,attribute lists>>

If `<caption>` is not specified then the displayed text is auto-generated:

- The AsciiDoc `xhtml11` backend displays the `<id>` enclosed in square brackets.
- If DocBook is produced the DocBook toolchain is responsible for the displayed text which will normally be the referenced figure, table or section title number followed by the element’s title text.

Here is an example:

    [[tiger_image]]
    .Tyger tyger
    image::tiger.png[]

    This can be seen in <<tiger_image>>.

#### 18.1.3. Linking to Local Documents

Hypertext links to files on the local file system are specified using the link inline macro.

    link:<target>[<caption>]

The link macro generates relative URLs. The link macro `<target>` is the target file name (relative to the file system location of the referring document). The optional `<caption>` is the link’s displayed text. If `<caption>` is not specified then `<target>` is displayed. Example:

    link:downloads/foo.zip[download foo.zip]

You can use the `<filename>#<id>` syntax to refer to an anchor within a target document but this usually only makes sense when targeting HTML documents.

Images can serve as hyperlinks using the `image` macro.

#### 18.1.4. Images

Inline images are inserted into the output document using the image macro. The inline syntax is:

    image:<target>[<attributes>]

The contents of the image file `<target>` is displayed. To display the image its file format must be supported by the target backend application. HTML and DocBook applications normally support PNG or JPG files.

`<target>` file name paths are relative to the location of the referring document.

Image macro attributes

- The optional first positional attribute list entry specifies the alternative text which is displayed if the output application is unable to process the image file. For example:

      image:images/logo.png[Company Logo]

- The optional `width` and `height` attributes scale the image size and can be used in any combination. The units are pixels. The following example scales the previous example to a height of 32 pixels:

      image:images/logo.png["Company Logo",height=32]

- The optional `link` attribute is used to link the image to an external document. The following example links a screenshot thumbnail to a full size version:

      image:screen-thumbnail.png[height=32,link="screen.png"]

- The optional `scaledwidth` attribute is only used in DocBook block images (specifically for PDF documents). The following example scales the images to 75% of the available print width:

      image::images/logo.png["Company Logo",scaledwidth="75%"]

- The optional `align` attribute is used for horizontal image alignment in DocBook block images (specifically for PDF documents). Allowed values are `center`, `left` and `right`. For example:

      image::images/tiger.png["Tiger image",align="left"]

#### 18.1.5. Comment Lines

See comment block macro.

### 18.2. Block Macros

A Block macro reference must be contained in a single line separated either side by a blank line or a block delimiter.

Block macros behave just like Inline macros, with the following differences:

- They occur in a block context.
- The default syntax is `<name>::<target>[<attrlist>]` (two colons, not one).
- Markup template section names end in `-blockmacro` instead of `-inlinemacro`.

#### 18.2.1. Block Identifier

The Block Identifier macro sets the `id` attribute and has the same syntax as the anchor inline macro since it performs essentially the same function — block templates employ the `id` attribute as a block link target. For example:

    [[X30]]

This is equivalent to the `[id="X30"]` block attribute list.

#### 18.2.2. Images

Formal titled images are inserted into the output document using the image macro. The syntax is:

    image::<target>[<attributes>]

The block `image` macro has the same macro attributes as its inline counterpart.

Images can be titled by preceding the `image` macro with a BlockTitle. DocBook toolchains normally number examples and generate a List of Figures backmatter section.

For example:

    .Main circuit board
    image::images/layout.png[J14P main circuit board]

A title prefix that can be inserted with the `caption` attribute (`xhtml11` and `html4` backends). For example:

    .Main circuit board
    [caption="Figure 2: "]
    image::images/layout.png[J14P main circuit board]

#### 18.2.3. Comment Lines

Single lines starting with two forward slashes hard up against the left margin are treated as comments. Comment lines do not appear in the output unless the showcomments attribute is defined. Comment lines have been implemented as both block and inline macros so a comment line can appear as a standalone block or within block elements that support inline macro expansion. Example comment line:

    // This is a comment.

If the showcomments attribute is defined comment lines are written to the output:

- The normal AsciiDoc inline text formatting is applied to comment lines.
- In DocBook the comment lines are enclosed by the remark element (which may or may not be rendered by your toolchain).
- The showcomments attribute does not expose Comment Blocks. Comment Blocks are never passed to the output.

### 18.3. System Macros

System macros are block macros that perform a predefined task and are hardwired into the `asciidoc(1)` program.

- You can escape system macros with a leading backslash character (as you can with other macros).
- The syntax and tasks performed by system macros is built into `asciidoc(1)` so they don’t appear in configuration files. You can however customize the syntax by adding entries to a configuration file `[macros]` section.

#### 18.3.1. Include Macros

The `include` and `include1` system macros to include the contents of a named file into the source document.

The `include` macro includes a file as if it were part of the parent document — tabs are expanded and system macros processed. The contents of `include1` files are not subject to tab expansion or system macro processing nor are attribute or lower priority substitutions performed. The `include1` macro’s intended use is to include verbatim embedded CSS or scripts into configuration file headers. Example:

    include::chapter1.txt[tabsize=4]

Include macro behavior

- If the included file name is specified with a relative path then the path is relative to the location of the referring document.
- Include macros can appear inside configuration files.
- Files included from within DelimitedBlocks are read to completion to avoid false end-of-block underline termination.
- Attribute references are expanded inside the include target; if an attribute is undefined then the included file is silently skipped.
- The tabsize macro attribute sets the number of space characters to be used for tab expansion in the included file (not applicable to `include1` macro).
- The depth macro attribute sets the maximum permitted number of subsequent nested includes (not applicable to `include1` macro which does not process nested includes). Setting depth to one disables nesting inside the included file. By default, nesting is limited to a depth of five.
- Internally the `include1` macro is translated to the `include1` system attribute which means it must be evaluated in a region where attribute substitution is enabled. To inhibit nested substitution in included files it is preferable to use the `include` macro and set the attribute `depth=1`.

#### 18.3.2. Conditional Inclusion Macros

Lines of text in the source document can be selectively included or excluded from processing based on the existence (or not) of a document attribute. There are two conditional inclusion macros; the first includes document text between the `ifdef` and `endif` macros if a document attribute is defined:

    ifdef::<attribute>[]
    :
    endif::<attribute>[]

The second includes document text between the `ifndef` and `endif` macros if the attribute is not defined:

    ifndef::<attribute>[]
    :
    endif::<attribute>[]

`<attribute>` is an attribute name which is optional in the trailing `endif` macro.

If you only want to process a single line of text then the text can be put inside the square brackets and the `endif` macro omitted, for example:

    ifdef::revision[Version number 42]

Is equivalent to:

    ifdef::revision[]
    Version number 42
    endif::revision[]

Take a look at the `*.conf` configuration files in the AsciiDoc distribution for examples of conditional inclusion macro usage.

#### 18.3.3. eval, sys and sys2 System Macros

These block macros exhibit the same behavior as their same named system attribute references. The difference is that system macros occur in a block macro context whereas system attributes are confined to an inline context where attribute substitution is enabled.

The following example displays a long directory listing inside a literal block:

    ------------------
    sys::[ls -l *.txt]
    ------------------

#### 18.3.4. Template System Macro

The `template` block macro allows the inclusion of one configuration file template section within another. The following example includes the `[admonitionblock]` section in the `[admonitionparagraph]` section:

    [admonitionparagraph]
    template::[admonitionblock]

Template macro behavior

- The `template::[]` macro is useful for factoring configuration file markup.
- `template::[]` macros cannot be nested.
- `template::[]` macro expansion is applied to all sections after all configuration files have been read.

### 18.4. Passthrough macros

Passthrough macros are analogous to passthrough blocks and are used to pass text directly to the output. The substitution performed on the text is determined by the macro definition but can be overridden by the `<subslist>`. The usual syntax is `<name>:<subslist>[<passtext>]` (for inline macros) and `<name>::<subslist>[<passtext>]` (for block macros).

pass

  Inline and block. Passes text unmodified apart from explicitly specified substitutions). Examples:

      pass:[<q>To be or not to be</q>]
      pass:attributes,quotes[<u>the '{author}'</u>]

asciimath, latexmath
  Inline and block. Passes text unmodified. Used for mathematical formulas.
+++

  Inline and block. The triple-plus passthrough is functionally identical to the pass macro but you don’t have to escape `]` characters and you can prefix with quoted attributes in the inline version. Example:

      Red [red]+++`sum_(i=1)\^n i=(n(n+1))/2`$+++ AsciiMathML formula

$$

  Inline and block. The double-dollar passthrough is functionally identical with one exception: special characters are escaped. Example:

      $$`[[a,b],[c,d]]((n),(k))`$$

`
  Text quoted with single backtick characters constitutes an inline literal passthrough. The enclosed text is rendered in a monospaced font and is only subject to special character substitution. This makes sense since monospace text is usually intended to be rendered literally and often contains characters that would otherwise have to be escaped. If you need monospaced text containing inline substitutions use a plus character instead of a backtick.

### 18.5. Macro Definitions

Each entry in the configuration `[macros]` section is a macro definition which can take one of the following forms:

`<pattern>=<name>[<subslist]`
  Inline macro definition.
`<pattern>=#<name>[<subslist]`
  Block macro definition.
`<pattern>=+<name>[<subslist]`
  System macro definition.
`<pattern>`
  Delete the existing macro with this `<pattern>`.

`<pattern>` is a Python regular expression and `<name>` is the name of a markup template. If `<name>` is omitted then it is the value of the regular expression match group named name. The optional `[<subslist]` is a comma-separated list of substitution names enclosed in `[]` brackets, it sets the default substitutions for passthrough text, if omitted then no passthrough substitutions are performed.

Pattern named groups. The following named groups can be used in macro `<pattern>` regular expressions and are available as markup template attributes:

name
  The macro name.
target
  The macro target.
attrlist
  The macro attribute list.
passtext
  Contents of this group are passed unmodified to the output subject only to subslist substitutions.
subslist
  Processed as a comma-separated list of substitution names for passtext substitution, overrides the the macro definition subslist.

Here’s what happens during macro substitution

- Each contextually relevant macro pattern from the `[macros]` section is matched against the input source line.
- If a match is found the text to be substituted is loaded from a configuration markup template section named like `<name>-inlinemacro` or `<name>-blockmacro` (depending on the macro type).
- Global and macro attribute list attributes are substituted in the macro’s markup template.
- The substituted template replaces the macro reference in the output document.

## 19. Tables

The AsciiDoc table syntax looks and behaves like other delimited block types and supports standard block configuration entries. Formatting is easy to read and, just as importantly, easy to enter.

- Cells and columns can be formatted using built-in customizable styles.
- Horizontal and vertical cell alignment can be set on columns and cell.
- Horizontal and vertical cell spanning is supported.

### 19.1. Example tables

Table 2. Simple table

1 | 2 | A
3 | 4 | B
5 | 6 | C

Example 5. AsciiDoc source

    [width="15%"]
    |=======
    |1 |2 |A
    |3 |4 |B
    |5 |6 |C
    |=======

Table 3. Columns formatted with strong, monospaced and emphasis styles

| Columns 2 and 3
--- | ---
footer 1 | `footer 2` | footer 3
1 | `Item 1` | Item 1
2 | `Item 2` | Item 2
3 | `Item 3` | Item 3
4 | `Item 4` | Item 4

Example 6. AsciiDoc source

    .An example table
    [width="50%",cols=">s,^m,e",frame="topbot",options="header,footer"]
    |==========================
    |      2+|Columns 2 and 3
    |1       |Item 1  |Item 1
    |2       |Item 2  |Item 2
    |3       |Item 3  |Item 3
    |4       |Item 4  |Item 4
    |footer 1|footer 2|footer 3
    |==========================

Table 4. Horizontal and vertical source data

Date | Duration | Avg HR | Notes
--- | --- | --- | ---
22-Aug-08 | 10:24 | 157 | Worked out MSHR (max sustainable heart rate) by going hard for this interval.
22-Aug-08 | 23:03 | 152 | Back-to-back with previous interval.
24-Aug-08 | 40:00 | 145 | Moderately hard interspersed with 3x 3min intervals (2min hard + 1min really hard taking the HR up to 160).

Short cells can be entered horizontally, longer cells vertically. The default behavior is to strip leading and trailing blank lines within a cell. These characteristics aid readability and data entry.

Example 7. AsciiDoc source

    .Windtrainer workouts
    [width="80%",cols="3,^2,^2,10",options="header"]
    |=========================================================
    |Date |Duration |Avg HR |Notes

    |22-Aug-08 |10:24 | 157 |
    Worked out MSHR (max sustainable heart rate) by going hard
    for this interval.

    |22-Aug-08 |23:03 | 152 |
    Back-to-back with previous interval.

    |24-Aug-08 |40:00 | 145 |
    Moderately hard interspersed with 3x 3min intervals (2min
    hard + 1min really hard taking the HR up to 160).

    |=========================================================

Table 5. A table with externally sourced CSV data

ID | Customer Name | Contact Name | Customer Address | Phone
--- | --- | --- | --- | ---
AROUT | Around the Horn | Thomas Hardy | 120 Hanover Sq. London | (171) 555-7788
BERGS | Berglunds snabbkop | Christina Berglund | Berguvsvagen 8 Lulea | 0921-12 34 65
BLAUS | Blauer See Delikatessen | Hanna Moos | Forsterstr. 57 Mannheim | 0621-08460
BLONP | Blondel pere et fils | Frederique Citeaux | 24, place Kleber Strasbourg | 88.60.15.31
BOLID | Bolido Comidas preparadas | Martin Sommer | C/ Araquil, 67 Madrid | (91) 555 22 82
BONAP | Bon app' | Laurence Lebihan | 12, rue des Bouchers Marseille | 91.24.45.40
BOTTM | Bottom-Dollar Markets | Elizabeth Lincoln | 23 Tsawassen Blvd. Tsawassen | (604) 555-4729
BSBEV | B’s Beverages | Victoria Ashworth | Fauntleroy Circus London | (171) 555-1212
CACTU | Cactus Comidas para llevar | Patricio Simpson | Cerrito 333 Buenos Aires | (1) 135-5555

Example 8. AsciiDoc source

    [format="csv",cols="^1,4*2",options="header"]
    |===================================================
    ID,Customer Name,Contact Name,Customer Address,Phone
    include::customers.csv[]
    |===================================================

Table 6. Cell spans, alignments and styles

1 | 2 | 3 | 4
5 | `6` | `7`
8
9 | `10`

Example 9. AsciiDoc source

    [cols="e,m,^,>s",width="25%"]
    |============================
    |1 >s|2 |3 |4
    ^|5 2.2+^.^|6 .3+<.>m|7
    ^|8
    |9 2+>|10
    |============================

### 19.2. Table input data formats

AsciiDoc table data can be psv, dsv or csv formatted. The default table format is psv.

AsciiDoc psv (Prefix Separated Values) and dsv (Delimiter Separated Values) formats are cell oriented — the table is treated as a sequence of cells — there are no explicit row separators.

- psv prefixes each cell with a separator whereas dsv delimits cells with a separator, that really the only difference (apart from different default separators).
- psv and dsv separators are Python regular expressions.
- The default psv separator contains cell specifier related named regular expression groups.
- The default dsv separator is `:|\n` (a colon or a line break).
- psv and dsv cell separators can be escaped by preceding them with a backslash character.

Here are four psv cells (the second item spans two columns; the last contains an escaped separator):

    |One 2+|Two and three |A \| separator character

csv is the quasi-standard row oriented Comma Separated Values (CSV) format commonly used to import and export spreadsheet and database data.

### 19.3. Table attributes

Individual tables are customized by an optional AttributeList preceding the table. Specify attributes when you want to change the default table format:

format
  psv (default), dsv or csv (See Table Data Formats).
separator
  The cell separator. A Python regular expression (psv and dsv formats) or a single character (csv format).
frame
  Defines the table border and can take the following values: topbot (top and bottom), all (all sides), none and sides (left and right sides). The default value is all.
grid
  Defines which ruler lines are drawn between table rows and columns. The grid attribute value can be any of the following values: none, cols, rows and all. The default value is all.
align
  Use the align attribute to vertically align all cells in a table. The following values are valid: left, right, and center (defaults to left). Overridden by Column specifiers and Cell specifiers.
valign
  Use the valign attribute to vertically align all cells in a table. The following values are valid: top, bottom, and middle (defaults to top). Overridden by Column specifiers and Cell specifiers.
options
  The options attribute can contain the following comma separated values: header, footer. By default header and footer rows are omitted.
cols

  The cols attribute is a comma separated list of column specifiers. For example `cols="2<p,2*,4p,>"`.

  - If cols is present it must specify all columns.
  - If the cols attribute is not specified the number of columns is calculated as the number of data items in the first line of the table.
  - The degenerate form for the cols attribute is an integer specifying the number of columns e.g. `cols=4`.
width
  The width attribute is expressed as a percentage value ("1%"…"99%"). The width specifies the table width relative to the available width. HTML outputs use this value directly. If width is specified DocBook uses the absolute widths (see calculated markup attributes ), if no width is specified all of the available width is used.
filter
  The filter attribute defines an external shell command that is invoked for each cell. The built-in asciidoc table style is implemented using a filter.

### 19.4. Column Specifiers

Column specifiers define how columns are rendered and appear in the table cols attribute. A column specifier consists of an optional column multiplier followed by optional alignment, width and style values and is formatted like:

    [<multiplier>*][<align>][<width>][<style>]

- All components are optional. The multiplier must be first and the style last. The order of `<align>` or `<width>` is not important.
- Column `<width>` can be either an integer proportional value (1…) or a percentage (1%…100%). The default value is 1. To ensure portability across different backends, there is no provision for absolute column widths (not to be confused with output column width markup attributes which are available in both percentage and absolute units).

- The <align> column alignment specifier is formatted like:

      [<horizontal>][.<vertical>]

  Where `<horizontal>` and `<vertical>` are one of the following characters: `<`, `^` or `>` which represent `left`, `center` and `right` horizontal alignment or `top`, `middle` and `bottom` vertical alignment respectively.

- A `<multiplier>` can be used to specify repeated columns e.g. `cols="4*<"` specifies four left-justified columns. Default value 1.
- The `<style>` name specifies a table style to used to markup column cells (you can use the full style names if you wish but the first letter is normally sufficient).
- Column specific styles are not applied to header row formatting.

### 19.5. Cell Specifiers

Cell specifiers allow individual cells in psv formatted tables to be spanned, multiplied, aligned and styled. Cell specifiers prefix psv `|` delimiters and are formatted like:

    [<span>*|+][<align>][<style>]

- <span> specifies horizontal and vertical cell spans (+ operator) or the number of times the cell is replicated (* operator). <span> is formatted like:

      [<colspan>][.<rowspan>]

  Where `<colspan>` and `<rowspan>` are integers specifying the number of columns and rows to span.

- `<align>` specifies horizontal and vertical cell alignment an is the same as in column specifiers.
- A `<style>` value is the first letter of table style name.

For example, the following psv formatted cell will span two columns and the text will be centered and emphasized:

    `2+^e| Cell text`

### 19.6. Table styles

Table styles can be applied to the entire table (by setting the style attribute in the table’s attribute list) or on a per column basis (by specifying the style in the table’s cols attribute). Tables come with the following predefined styles:

default
  The default style: AsciiDoc inline text formatting; blank lines are treated as paragraph breaks.
emphasis
  Like default but all text is emphasised.
monospaced
  Like default but all text is in a monospaced font. TODO: This doesn’t work in DocBook.
strong
  Like default but all text is bold.
asciidoc
  With this style table cells can contain any of the AsciiDoc elements that are allowed inside document sections. This style runs `asciidoc(1)` as a filter to process cell contents. See also Docbook table limitations.
literal
  No text formatting; monospaced font; all line breaks are retained (like AsciiDoc LiteralBlock).
verse
  Text formatting; all line breaks are retained (c.f. AsciiDoc delimited block verse style).

### 19.7. Markup attributes

AsciiDoc makes a number of attributes available to table markup templates and tags. Both absolute and percentage width values are available. Column specific attributes are available when substituting the colspec cell data tags.

pageunits
  Only used by DocBook, defaults to pt.
pagewidth
  The nominal output page width in pageunit units. Used to calculate table and column widths. Only used by DocBook, defaults to 425.
tableabswidth
  Integer value calculated from width and pagewidth attributes. In pageunit units.
tablepcwidth
  Table width expressed as a percentage of the available width. Integer value (0..100).
colabswidth
  Integer value calculated from cols column width, width and pagewidth attributes. In pageunit units.
colpcwidth
  Column width expressed as a percentage of the table width. Integer value (0..100).
colcount
  Total number of table columns.
rowcount
  Total number of table rows.
align
  left, right or center.
valign
  top, bottom or middle.
colnumber, colstart
  The number of the leftmost column occupied by the cell (1…).
colend
  The number of the rightmost column occupied by the cell (1…).
colspan
  Number of columns the cell should span.
rowspan
  Number of rows the cell should span (1…).
morerows
  Number of additional rows the cell should span (0…).

### 19.8. Nested tables

An alternative table syntax using a ! character instead of a | character is provided to allow a single level of table nesting. Columns containing nested tables must use the asciidoc style. An example can be found in `./examples/website/newtables.txt`.

### 19.9. DocBook table limitations

Fully implementing tables is not trivial, some DocBook toolchains do better than others. AsciiDoc HTML table outputs are rendered correctly in all the popular browsers — if your DocBook generated tables don’t look right compare them with the output generated by the AsciiDoc xhtml11 backend or try a different DocBook toolchain. Here is a list of things to be aware of:

- Although nested tables are not legal in DocBook 4 the FOP and dblatex toolchains will process them correctly. If you use `a2x(1)` you will need to include the `--no-xmllint` option to suppress DocBook validation errors.

  Technically you can nest DocBook 4 tables one level using the entrytbl element, but not all toolchains process entrytbl.

- DocBook only allows a subset of block elements inside table cells so not all AsciiDoc elements produce valid DocBook inside table cells. If you get validation errors running `a2x(1)` try the `--no-xmllint` option, toolchains will often process nested block elements such as sidebar blocks and floating titles correctly.
- Text formatting in cells using the monospaced table style will raise validation errors because the DocBook literal element was not designed to support formatted text (using the literal element is a kludge on the part of AsciiDoc as there is no easy way to set the font style in DocBook.
- Cell alignments are ignored for verse, literal or asciidoc table styles.

## 20. Manpage Documents

Sooner or later, if you program for a UNIX environment, you’re going to have to write a man page.

By observing a couple of additional conventions you can compose AsciiDoc files that will translate to a DocBook refentry (man page) document. The resulting DocBook file can then be translated to the native roff man page format (or other formats).

For example, the `asciidoc.1.txt` file in the AsciiDoc distribution `./doc` directory was used to generate both the `asciidoc.1.css-embedded.html` HTML file the `asciidoc.1` roff formatted `asciidoc(1)` man page.

To find out more about man pages view the `man(7)` manpage (`man 7 man` and `man man-pages` commands).

### 20.1. Document Header

A document Header is mandatory. The title line contains the man page name followed immediately by the manual section number in brackets, for example ASCIIDOC(1). The title name should not contain white space and the manual section number is a single digit optionally followed by a single character.

### 20.2. The NAME Section

The first manpage section is mandatory, must be titled NAME and must contain a single paragraph (usually a single line) consisting of a list of one or more comma separated command name(s) separated from the command purpose by a dash character. The dash must have at least one white space character on either side. For example:

    printf, fprintf, sprintf - print formatted output

### 20.3. The SYNOPSIS Section

The second manpage section is mandatory and must be titled SYNOPSIS.

### 20.4. refmiscinfo attributes

In addition to the automatically created man page intrinsic attributes you can assign DocBook refmiscinfo element source, version and manual values using AsciiDoc `{mansource}`, `{manversion}` and `{manmanual}` attributes respectively. This example is from the AsciiDoc header of a man page source file:

    :man source:   AsciiDoc
    :man version:  {revision}
    :man manual:   AsciiDoc Manual

## 21. Mathematical Formulas

The asciimath and latexmath passthrough macros along with asciimath and latexmath passthrough blocks provide a (backend dependent) mechanism for rendering mathematical formulas. You can use the following math markups:

The latexmath macro used to include LaTeX Math in DocBook outputs is not the same as the latexmath macro used to include LaTeX MathML in XHTML outputs. LaTeX Math applies to DocBook outputs that are processed by dblatex and is normally used to generate PDF files. LaTeXMathML is very much a subset of LaTeX Math and applies to XHTML documents.

### 21.1. LaTeX Math

LaTeX math can be included in documents that are processed by dblatex(1). Example inline formula:

    latexmath:[$C = \alpha + \beta Y^{\gamma} + \epsilon$]

For more examples see the AsciiDoc website or the distributed `doc/latexmath.txt` file.

### 21.2. ASCIIMathML

ASCIIMathML formulas can be included in XHTML documents generated using the xhtml11 backend. To enable ASCIIMathML support you must define the asciimath attribute, for example using the `-a asciimath` command-line option. Example inline formula:

    asciimath:[`x/x={(1,if x!=0),(text{undefined},if x=0):}`]

For more examples see the AsciiDoc website or the distributed `doc/asciimathml.txt` file.

### 21.3. LaTeXMathML

LaTeXMathML allows LaTeX Math style formulas to be included in XHTML documents generated using the AsciiDoc xhtml11 backend. AsciiDoc uses the original LaTeXMathML by Douglas Woodall. LaTeXMathML is derived from ASCIIMathML and is for users who are more familiar with or prefer using LaTeX math formulas (it recognizes a subset of LaTeX Math, the differences are documented on the LaTeXMathML web page). To enable LaTeXMathML support you must define the latexmath attribute, for example using the `-a latexmath` command-line option. Example inline formula:

    latexmath:[$\sum_{n=1}^\infty \frac{1}{2^n}$]

For more examples see the AsciiDoc website or the distributed `doc/latexmathml.txt` file.

There are more examples on the AsciiDoc website.

### 21.4. MathML

MathML is a low level XML markup for mathematics. AsciiDoc has no macros for MathML but users familiar with this markup could use passthrough macros and passthrough blocks to include MathML in output documents.

## 22. Configuration Files

AsciiDoc source file syntax and output file markup is largely controlled by a set of cascading, text based, configuration files. At runtime The AsciiDoc default configuration files are combined with optional user and document specific configuration files.

### 22.1. Configuration File Format

Configuration files contain named sections. Each section begins with a section name in square brackets []. The section body consists of the lines of text between adjacent section headings.

- Section names consist of one or more alphanumeric, underscore or dash characters and cannot begin or end with a dash.
- Lines starting with a hash character "#" are treated as comments and ignored.
- Same named sections and section entries override previously loaded sections and section entries (this is sometimes referred to as cascading). Consequently, downstream configuration files need only contain those sections and section entries that need to be overridden.

When creating custom configuration files you only need to include the sections and entries that differ from the default configuration.

The best way to learn about configuration files is to read the default configuration files in the AsciiDoc distribution in conjunction with `asciidoc(1)` output files. You can view configuration file load sequence by turning on the `asciidoc(1)` `-v` (`--verbose`) command-line option.

AsciiDoc reserves the following section names for specific purposes:

miscellaneous
  Configuration options that don’t belong anywhere else.
attributes
  Attribute name/value entries.
specialcharacters
  Special characters reserved by the backend markup.
tags
  Backend markup tags.
quotes
  Definitions for quoted inline character formatting.
specialwords
  Lists of words and phrases singled out for special markup.
replacements, replacements2
  Find and replace substitution definitions.
specialsections
  Used to single out special section names for specific markup.
macros
  Macro syntax definitions.
titles
  Heading, section and block title definitions.
paradef-*
  Paragraph element definitions.
blockdef-*
  DelimitedBlock element definitions.
listdef-*
  List element definitions.
listtags-*
  List element tag definitions.
tabledef-*
  Table element definitions.
tabletags-*
  Table element tag definitions.

Each line of text in these sections is a section entry. Section entries share the following syntax:

name=value
  The entry value is set to value.
name=
  The entry value is set to a zero length string.
name!
  The entry is undefined (deleted from the configuration). This syntax only applies to attributes and miscellaneous sections.

Section entry behavior

- All equals characters inside the `name` must be escaped with a backslash character.
- `name` and `value` are stripped of leading and trailing white space.
- Attribute names, tag entry names and markup template section names consist of one or more alphanumeric, underscore or dash characters. Names should not begin or end with a dash.
- A blank configuration file section (one without any entries) deletes any preceding section with the same name (applies to non-markup template sections).

### 22.2. Miscellaneous section

The optional `[miscellaneous]` section specifies the following `name=value` options:

newline

  Output file line termination characters. Can include any valid Python string escape sequences. The default value is `\r\n` (carriage return, line feed). Should not be quoted or contain explicit spaces (use `\x20` instead). For example:

      $ asciidoc -a 'newline=\n' -b docbook mydoc.txt

outfilesuffix
  The default extension for the output file, for example `outfilesuffix=.html`. Defaults to backend name.
tabsize
  The number of spaces to expand tab characters, for example `tabsize=4`. Defaults to 8. A tabsize of zero suppresses tab expansion (useful when piping included files through block filters). Included files can override this option using the tabsize attribute.
pagewidth, pageunits
  These global table related options are documented in the Table Configuration File Definitions sub-section.

`[miscellaneous]` configuration file entries can be set using the `asciidoc(1)` `-a` (`--attribute`) command-line option.

### 22.3. Titles section

sectiontitle
  Two line section title pattern. The entry value is a Python regular expression containing the named group title.
underlines

  A comma separated list of document and section title underline character pairs starting with the section level 0 and ending with section level 4 underline. The default setting is:

      underlines="==","--","~~","^^","++"

sect0…sect4
  One line section title patterns. The entry value is a Python regular expression containing the named group title.
blocktitle
  BlockTitle element pattern. The entry value is a Python regular expression containing the named group title.
subs
  A comma separated list of substitutions that are performed on the document header and section titles. Defaults to normal substitution.

### 22.4. Tags section

The `[tags]` section contains backend tag definitions (one per line). Tags are used to translate AsciiDoc elements to backend markup.

An AsciiDoc tag definition is formatted like `<tagname>=<starttag>|<endtag>`. For example:

    emphasis=<em>|</em>

In this example `asciidoc(1)` replaces the | character with the emphasized text from the AsciiDoc input file and writes the result to the output file.

Use the `{brvbar}` attribute reference if you need to include a | pipe character inside tag text.

### 22.5. Attributes section

The optional `[attributes]` section contains predefined attributes.

If the attribute value requires leading or trailing spaces then the text text should be enclosed in quotation mark (") characters.

To delete a attribute insert a `name!` entry in a downstream configuration file or use the `asciidoc(1)` `--attribute name!` command-line option (an attribute name suffixed with a `!` character deletes the attribute)

### 22.6. Special Characters section

The `[specialcharacters]` section specifies how to escape characters reserved by the backend markup. Each translation is specified on a single line formatted like:

    special_character=translated_characters

Special characters are normally confined to those that resolve markup ambiguity (in the case of SGML/XML markups the ampersand, less than and greater than characters). The following example causes all occurrences of the `<` character to be replaced by `&lt;`.

    <=&lt;

### 22.7. Quoted Text section

Quoting is used primarily for text formatting. The `[quotes]` section defines AsciiDoc quoting characters and their corresponding backend markup tags. Each section entry value is the name of a of a `[tags]` section entry. The entry name is the character (or characters) that quote the text. The following examples are taken from AsciiDoc configuration files:

    [quotes]
    _=emphasis

    [tags]
    emphasis=<em>|</em>

You can specify the left and right quote strings separately by separating them with a | character, for example:

    ``|''=quoted

Omitting the tag will disable quoting, for example, if you don’t want superscripts or subscripts put the following in a custom configuration file or edit the global `asciidoc.conf` configuration file:

    [quotes]
    ^=
    ~=

Unconstrained quotes are differentiated by prefixing the tag name with a hash character, for example:

    __=#emphasis

Quoted text behavior

- Quote characters must be non-alphanumeric.
- To minimize quoting ambiguity try not to use the same quote characters in different quote types.

### 22.8. Special Words section

The `[specialwords]` section is used to single out words and phrases that you want to consistently format in some way throughout your document without having to repeatedly specify the markup. The name of each entry corresponds to a markup template section and the entry value consists of a list of words and phrases to be marked up. For example:

    [specialwords]
    strongwords=NOTE: IMPORTANT:

    [strongwords]
    <strong>{words}</strong>

The examples specifies that any occurrence of `NOTE:` or `IMPORTANT:` should appear in a bold font.

Words and word phrases are treated as Python regular expressions: for example, the word `^NOTE:` would only match `NOTE:` if appeared at the start of a line.

AsciiDoc comes with three built-in Special Word types: emphasizedwords, monospacedwords and strongwords, each has a corresponding (backend specific) markup template section. Edit the configuration files to customize existing Special Words and to add new ones.

Special word behavior

- Word list entries must be separated by space characters.
- Word list entries with embedded spaces should be enclosed in quotation (") characters.
- A `[specialwords]` section entry of the form `name=word1 [word2…]` adds words to existing `name` entries.
- A `[specialwords]` section entry of the form `name` undefines (deletes) all existing `name` words.
- Since word list entries are processed as Python regular expressions you need to be careful to escape regular expression special characters.
- By default Special Words are substituted before Inline Macros, this may lead to undesirable consequences. For example the special word `foobar` would be expanded inside the macro call `http://www.foobar.com[]`. A possible solution is to emphasize whole words only by defining the word using regular expression characters, for example `\bfoobar\b`.
- If the first matched character of a special word is a backslash then the remaining characters are output without markup i.e. the backslash can be used to escape special word markup. For example the special word `\\?\b[Tt]en\b` will mark up the words `Ten` and `ten` only if they are not preceded by a backslash.

### 22.9. Replacements section

`[replacements]` and `[replacements2]` configuration file entries specify find and replace text and are formatted like:

    find_pattern=replacement_text

The find text can be a Python regular expression; the replace text can contain Python regular expression group references.

Use Replacement shortcuts for often used macro references, for example (the second replacement allows us to backslash escape the macro name):

    NEW!=image:./images/smallnew.png[New!]
    \\NEW!=NEW!

Replacement behavior

- The built-in replacements can be escaped with a backslash.
- If the find or replace text has leading or trailing spaces then the text should be enclosed in quotation (") characters.
- Since the find text is processed as a regular expression you need to be careful to escape regular expression special characters.
- Replacements are performed in the same order they appear in the configuration file replacements section.

### 22.10. Markup Template Sections

Markup template sections supply backend markup for translating AsciiDoc elements. Since the text is normally backend dependent you’ll find these sections in the backend specific configuration files. Template sections differ from other sections in that they contain a single block of text instead of per line name=value entries. A markup template section body can contain:

- Attribute references
- System macro calls.
- A document content placeholder

The document content placeholder is a single | character and is replaced by text from the source element. Use the `{brvbar}` attribute reference if you need a literal | character in the template.

### 22.11. Configuration File Names and Locations

Configuration files have a `.conf` file name extension; they are loaded implicitly (using predefined file names and locations) or explicitly (using the `asciidoc(1)` `-f` (`--conf-file`) command-line option).

Implicit configuration files are loaded from the following directories in the following order:

1. The global configuration directory (normally `/etc/asciidoc` or `/usr/local/etc/asciidoc`) if it exists.
2. The directory containing the asciidoc executable.
3. The user’s `$HOME/.asciidoc` directory (if it exists).
4. The directory containing the AsciiDoc source file.

The following implicit configuration files from each of the above locations are loaded in the following order:

1. `asciidoc.conf`
2. `<backend>.conf`
3. `<backend>-<doctype>.conf`
4. `lang-<lang>.conf`

Where `<backend>` and `<doctype>` are values specified by the `asciidoc(1)` `-b` (`--backend`) and `-d` (`--doctype`) command-line options. `<lang>` is the value of the AsciiDoc `lang` attribute (defaults to `en` (English)).

Finally, configuration files named like the source file will be automatically loaded if they are found in the source file directory. For example if the source file is `mydoc.txt` and the `--backend=html4` option is used then `asciidoc(1)` will look for `mydoc.conf` and `mydoc-html4.conf` in that order.

Implicit configuration files that don’t exist will be silently skipped.

The user can explicitly specify additional configuration files using the `asciidoc(1)` `-f` (`--conf-file`) command-line option. The `-f` option can be specified multiple times, in which case configuration files will be processed in the order they appear on the command-line.

For example, when we translate our AsciiDoc document `mydoc.txt` with:

    $ asciidoc -f extra.conf mydoc.txt

Configuration files (if they exist) will be processed in the following order:

1. First default global configuration files from the asciidoc program directory are loaded:

       asciidoc.conf
       xhtml11.conf

2. Then, from the users home `~/.asciidoc` directory. This is were you put customization specific to your own asciidoc documents:

       asciidoc.conf
       xhtml11.conf
       xhtml11-article.conf

3. Next from the source document project directory (the first three apply to all documents in the directory, the last two are specific to the mydoc.txt document):

       asciidoc.conf
       xhtml11.conf
       xhtml11-article.conf
       mydoc.conf
       mydoc-xhtml11.conf

4. Finally the file specified by the `-f` command-line option is loaded:

       extra.conf

Use the `asciidoc(1)` `-v` (`--verbose`) command-line option to see which configuration files are loaded and the order in which they are loaded.

## 23. Document Attributes

A document attribute is comprised of a name and a textual value and is used for textual substitution in AsciiDoc documents and configuration files. An attribute reference (an attribute name enclosed in braces) is replaced by its corresponding attribute value.

There are four sources of document attributes (from highest to lowest precedence):

- Command-line attributes.
- AttributeEntry, AttributeList, Macro and BlockId elements.
- Configuration file `[attributes]` sections.
- Intrinsic attributes.

Within each of these divisions the last processed entry takes precedence.

If an attribute is not defined then the line containing the attribute reference is dropped. This property is used extensively in AsciiDoc configuration files to facilitate conditional markup generation.

## 24. Attribute Entries

The `AttributeEntry` block element allows document attributes to be assigned within an AsciiDoc document. Attribute entries are added to the global document attributes dictionary. The attribute name/value syntax is a single line like:

    :<name>: <value>

For example:

    :Author Initials: JB

This will set an attribute reference `{authorinitials}` to the value JB in the current document.

To delete (undefine) an attribute use the following syntax:

    :<name>!:

AttributeEntry behavior

- The attribute entry line begins with colon — no white space allowed in left margin.
- AsciiDoc converts the `<name>` to a legal attribute name (lower case, alphanumeric and dash characters only — all other characters deleted). This allows more reader friendly text to be used.
- Leading and trailing white space is stripped from the `<value>`.
- If the `<value>` is blank then the corresponding attribute value is set to an empty string.
- Special characters in the entry `<value>` are substituted. You can enter special characters using character entity values, for example `&amp;`.
- Attribute references contained in the entry `<value>` will be expanded.
- By default AttributeEntry values are substituted for `specialcharacters` and `attributes` (see above), if you want a different AttributeEntry substitution set the `attributeentry-subs` attribute.
- Attribute entries in the document Header are available for header markup template substitution.
- Attribute elements override configuration file and intrinsic attributes but do not override command-line attributes. Here are some more attribute entry examples:

    AsciiDoc User Manual
    ====================
    :Author:    Stuart Rackham
    :Email:     srackham@gmail.com
    :Date:      April 23, 2004
    :Revision:  5.1.1
    :Key words: linux, ralink, debian, wireless
    :Revision history:

Which creates these attributes:

    {author}, {firstname}, {lastname}, {authorinitials}, {email},
    {date}, {revision}, {keywords}, {revisionhistory}

The preceding example is equivalent to the standard AsciiDoc two line document header. Actually it’s a little bit different with the addition of the `{keywords}` and `{revisionhistory}` attributes [4].

### 24.1. Setting configuration entries

A variant of the Attribute Entry syntax allows configuration file entries to be set from within an AsciiDoc document:

    :<section_name>.<entry_name>: <entry_value>

Where `<section_name>` is the configuration section name, `<entry_name>` is the name of the entry and `<entry_value>` is the optional entry value. This example sets the default labeled list style to horizontal:

    :listdef-labeled.style: horizontal

It is exactly equivalent to a configuration file containing:

    [listdef-labeled]
    style=horizontal

## 25. Attribute Lists

An attribute list is a comma separated list of attribute values. The entire list is enclosed in square brackets. Attribute lists are used to pass parameters to macros, blocks and inline quotes:

- The list consists of zero or more positional attribute values followed by zero or more named attribute values.
- Attribute values are enclosed in quotation mark (") characters.
- If the attribute list only contains positional attribute values and the values contain no commas then quoting is unnecessary.

Here are three examples (a single unquoted positional attribute; three unquoted attribute values; one positional attribute followed by two named attributes):

    [Hello]
    [quote, Bertrand Russell, The World of Mathematics (1956)]
    ["22 times", backcolor="#0e0e0e", options="noborders,wide"]

Attribute list behavior

- If one or more attribute values contains a comma the all values must be quoted (enclosed in quotation characters).
- If the list contains any named or quoted attributes then all string attribute values must be quoted.
- To include a quotation mark (") character in a quoted attribute value the the quotation mark must be escaped with a backslash.
- List attributes take precedence over existing attributes.
- List attributes can only be referenced in configuration file markup templates and tags, they are not available inside the document.
- Attribute references are allowed inside attribute lists — this is the only substitution performed on attribute lists.
- Setting a named attribute to `None` undefines the attribute.
- Positional attributes are referred to as `{1}`,`{2}`,`{3}`,…
- Attribute `{0}` refers to the entire list (excluding the enclosing square brackets).
- Attribute lists are evaluated as a list of Python function arguments. If this fails or any of the items do not evaluate to a string, a number or None then all list items are treated as string literals.

### 25.1. Options attribute

If the attribute list contains an attribute named `options` it is processed as a comma separated list of option names:

- Each name generates an attribute named like `<option>-option` (where `<option>` is the option name) with an empty string value. For example `[options="opt1,opt2,opt3"]` is equivalent to setting the following three attributes `[opt1-option="",opt2-option="",opt2-option=""]`.
- If you define a an option attribute globally (for example with an attribute entry) then it will apply to all elements in the document.
- AsciiDoc implements a number of predefined options which are listed in the Attribute Options appendix.

### 25.2. Macro Attribute lists

Macros calls are suffixed with an attribute list. The list may be empty but it cannot be omitted. List entries are used to pass attribute values to macro markup templates.

## 26. Attribute References

An attribute references is an attribute name (possibly followed by an additional parameters) enclosed in braces. When an attribute reference is encountered it is evaluated and replaced by its corresponding text value. If the attribute is undefined the line containing the attribute is dropped.

There are three types of attribute reference: Simple, Conditional and System.

Attribute reference behavior

- You can suppress attribute reference expansion by placing a backslash character immediately in front of the opening brace character.
- By default attribute references are not expanded in LiteralParagraphs, ListingBlocks or LiteralBlocks.

### 26.1. Simple Attributes References

Simple attribute references take the form `{<name>}`. If the attribute name is defined its text value is substituted otherwise the line containing the reference is dropped from the output.

### 26.2. Conditional Attribute References

Additional parameters are used in conjunction with the attribute name to calculate a substitution value. Conditional attribute references take the following forms:

`{<name>=<value>}`
  `<value>` is substituted if the attribute `<name>` is undefined otherwise its value is substituted. `<value>` can contain simple attribute references.
`{<name>?<value>}`
  `<value>` is substituted if the attribute `<name>` is defined otherwise an empty string is substituted. `<value>` can contain simple attribute references.
`{<name>!<value>}`
  `<value>` is substituted if the attribute `<name>` is undefined otherwise an empty string is substituted. `<value>` can contain simple attribute references.
`{<name>#<value>}`
  `<value>` is substituted if the attribute `<name>` is defined otherwise the undefined attribute entry causes the containing line to be dropped. `<value>` can contain simple attribute references.
`{<name>%<value>}`
  `<value>` is substituted if the attribute `<name>` is not defined otherwise the containing line is dropped. `<value>` can contain simple attribute references.
`{<name>@<regexp>:<value1>[:<value2>]}`
  `<value1>` is substituted if the value of attribute `<name>` matches the regular expression `<regexp>` otherwise `<value2>` is substituted. If attribute `<name>` is not defined the containing line is dropped. If `<value2>` is omitted an empty string is assumed. The values and the regular expression can contain simple attribute references. To embed colons in the values or the regular expression escape them with backslashes.
`{<name>$<regexp>:<value1>[:<value2>]}`

  Same behavior as the previous ternary attribute except for the following cases:

  `{<name>$<regexp>:<value>}`
    Substitutes `<value>` if `<name>` matches `<regexp>` otherwise the result is undefined and the containing line is dropped.
  `{<name>$<regexp>::<value>}`
    Substitutes `<value>` if `<name>` does not match `<regexp>` otherwise the result is undefined and the containing line is dropped.

#### 26.2.1. Conditional attribute examples

Conditional attributes are mainly used in AsciiDoc configuration files — see the distribution `.conf` files for examples.

Attribute equality test

  If `{backend}` is `docbook` or `xhtml11` the example evaluates to “DocBook or XHTML backend” otherwise it evaluates to “some other backend”:

      {backend@docbook|xhtml11:DocBook or XHTML backend:some other backend}

Attribute value map

  This example maps the `frame` attribute values [`topbot`, `all`, `none`, `sides`] to [`hsides`, `border`, `void`, `vsides`]:

      {frame@topbot:hsides}{frame@all:border}{frame@none:void}{frame@sides:vsides}

### 26.3. System Attribute References

System attribute references generate the attribute text value by executing a predefined action that is parametrized by a single argument. The syntax is `{<action>:<argument>}`.

`{eval:<expression>}`
  Substitutes the result of the Python `<expression>`. If `<expression>` evaluates to `None` or `False` the reference is deemed undefined and the line containing the reference is dropped from the output. If the expression evaluates to `True` the attribute evaluates to an empty string. In all remaining cases the attribute evaluates to a string representation of the `<expression>` result.
`{include:<filename>}`

  Substitutes contents of the file named `<filename>`.

  - The included file is read at the time of attribute substitution.
  - If the file does not exist a warning is emitted and the line containing the reference is dropped from the output file.
  - Tabs are expanded based on the current tabsize attribute value.
`{sys:<command>}`
  Substitutes the stdout generated by the execution of the shell `<command>`.
`{sys2:<command>}`
  Substitutes the stdout and stderr generated by the execution of the shell `<command>`.

System reference behavior

- System attribute arguments can contain non-system attribute references.
- Closing brace characters inside system attribute arguments must be escaped them with a backslash.

## 27. Intrinsic Attributes

Intrinsic attributes are simple attributes that are created automatically from AsciiDoc document header parameters, `asciidoc(1)` command-line arguments, execution parameters along with attributes defined in the default configuration files. Here’s the list of predefined intrinsic attributes:

    {amp}                 ampersand (&) character
    {asciidoc-dir}        the asciidoc(1) application directory
    {asciidoc-file}       the full path name of the asciidoc(1) script
    {asciidoc-version}    the version of asciidoc(1)
    {author}              author's full name
    {authored}            empty string '' if {author} or {email} defined,
    {authorinitials}      author initials (from document header)
    {backend-<backend>}   empty string ''
    {<backend>-<doctype>} empty string ''
    {backend}             document backend specified by `-b` option
    {backslash}           backslash character
    {basebackend-<base>}  empty string ''
    {basebackend}         html or docbook
    {brvbar}              broken vertical bar (|) character
    {date}                document date (from document header)
    {docdate}             document last modified date
    {doctime}             document last modified time
    {docname}             document file name without extension
    {docfile}             document file name  (note 5)
    {docdir}              document input directory name  (note 5)
    {doctitle}            document title (from document header)
    {doctype-<doctype>}   empty string ''
    {doctype}             document type specified by `-d` option
    {email}               author's email address (from document header)
    {empty}               empty string ''
    {encoding}            specifies input and output encoding
    {filetype-<fileext>}  empty string ''
    {filetype}            output file name file extension
    {firstname}           author first name (from document header)
    {gt}                  greater than (>) character
    {id}                  running block id generated by BlockId elements
    {indir}               input file directory name (note 2,5)
    {infile}              input file name (note 2,5)
    {lastname}            author last name (from document header)
    {level}               title level 1..4 (in section titles)
    {listindex}           the list index (1..) of the most recent list item
    {localdate}           the current date
    {localtime}           the current time
    {lt}                  less than (<) character
    {manname}             manpage name (defined in NAME section)
    {manpurpose}          manpage (defined in NAME section)
    {mantitle}            document title minus the manpage volume number
    {manvolnum}           manpage volume number (1..8) (from document header)
    {middlename}          author middle name (from document header)
    {nbsp}                Non-breaking space entity
    {outdir}              document output directory name (note 2)
    {outfile}             output file name (note 2)
    {reftext}             running block xreflabel generated by BlockId elements
    {revision}            document revision number (from document header)
    {sectnum}             formatted section number (in section titles)
    {showcomments}        send comment lines to the output
    {title}               section title (in titled elements)
    {two_colons}          Two colon characters
    {two_semicolons}      Two semicolon characters
    {user-dir}            the ~/.asciidoc directory (if it exists)
    {verbose}             defined as '' if --verbose command option specified

NOTES

1. Intrinsic attributes are global so avoid defining custom attributes with the same names.
2. `{outfile}`, `{outdir}`, `{infile}`, `{indir}` attributes are effectively read-only (you can set them but it won’t affect the input or output file paths).
3. See also the xhtml11 subsection for attributes that relate to AsciiDoc XHTML file generation.
4. The entries that translate to blank strings are designed to be used for conditional text inclusion. You can also use the `ifdef`, `ifndef` and `endif` System macros for conditional inclusion. [5]
5. `{docfile}` and `{docdir}` refer to root document specified on the `asciidoc(1)` command-line; `{infile}` and `{indir}` refer to the current input file which may be the root document or an included file. While the input is being read from the standard input (`stdin`) these attributes are undefined.

## 28. Block Element Definitions

The syntax and behavior of Paragraph, DelimitedBlock, List and Table block elements is determined by block definitions contained in AsciiDoc configuration file sections.

Each definition consists of a section title followed by one or more section entries. Each entry defines a block parameter controlling some aspect of the block’s behavior. Here’s an example:

    [blockdef-listing]
    delimiter=^-{4,}$
    template=listingblock
    presubs=specialcharacters,callouts

AsciiDoc Paragraph, DelimitedBlock, List and Table block elements share a common subset of configuration file parameters:

delimiter
  A Python regular expression that matches the first line of a block element — in the case of DelimitedBlocks it also matches the last line. Table elements don’t have an explicit delimiter — they synthesize their delimiters at runtime.
template
  The name of the configuration file markup template section that will envelope the block contents. The pipe | character is substituted for the block contents. List elements use a set of (list specific) tag parameters instead of a single template.
options
  A comma delimited list of element specific option names. In addition to being used internally, options are available during markup tag and template substitution as attributes with an empty string value named like `<option>-option` (where `<option>` is the option name).
subs, presubs, postsubs
  - presubs and postsubs are lists of comma separated substitutions that are performed on the block contents. presubs is applied first, postsubs (if specified) second.
  - subs is an alias for presubs.
  - If a filter is allowed (Paragraphs, DelimitedBlocks and Tables) and has been specified then presubs and postsubs substitutions are performed before and after the filter is run respectively.
  - Allowed values: specialcharacters, quotes, specialwords, replacements, macros, attributes, callouts.

  - The following composite values are also allowed:

    none
      No substitutions.
    normal
      The following substitutions: specialcharacters,quotes,attributes,specialwords, replacements,macros.
    verbatim
      specialcharacters and callouts substitutions.
  - normal and verbatim substitutions can be redefined by with `subsnormal` and `subsverbatim` entries in a configuration file `[miscellaneous]` section.
  - The substitutions are processed in the order in which they are listed and can appear more than once.
filter
  This optional entry specifies an executable shell command for processing block content (Paragraphs, DelimitedBlocks and Tables). The filter command can contain attribute references.
posattrs

  Optional comma separated list of positional attribute names. This list maps positional attributes (in the block’s attribute list) to named block attributes. The following example, from the QuoteBlock definition, maps the first and section positional attributes:

      posattrs=attribution,citetitle

style
  This optional parameter specifies the default style name.
<stylename>-style
  Optional style definition (see Styles below).

The following block parameters behave like document attributes and can be set in block attribute lists and style definitions: template, options, subs, presubs, postsubs, filter.

### 28.1. Styles

A style is a set of block attributes bundled as a single named attribute. The following example defines a style named verbatim:

    verbatim-style=template="literalblock",subs="verbatim"

- All style parameter names must be suffixed with `-style` and the style parameter value is in the form of a list of named attributes.
- Multi-item style attributes (subs,presubs,postsubs,posattrs) must be specified using Python tuple syntax rather than a simple list of values as they in separate entries e.g. `postsubs=("callouts",)` not `postsubs="callouts"`.

### 28.2. Paragraphs

Paragraph translation is controlled by `[paradef*]` configuration file section entries. Users can define new types of paragraphs and modify the behavior of existing types by editing AsciiDoc configuration files.

Here is the shipped Default paragraph definition:

    [paradef-default]
    delimiter=(?P<text>\S.*)
    template=paragraph

The Default paragraph definition has a couple of special properties:

1. It must exist and be defined in a configuration file section named `[paradef-default]`.
2. Irrespective of its position in the configuration files default paragraph document matches are attempted only after trying all other paragraph types.

Paragraph specific block parameter notes:

delimiter
  This regular expression must contain the named group text which matches the text on the first line. Paragraphs are terminated by a blank line, the end of file, or the start of a DelimitedBlock.
options
  The listelement option specifies that paragraphs of this type will automatically be considered part of immediately preceding list items.

Paragraph processing proceeds as follows:

1. The paragraph text is aligned to the left margin.
2. Optional presubs inline substitutions are performed on the paragraph text.
3. If a filter command is specified it is executed and the paragraph text piped to its standard input; the filter output replaces the paragraph text.
4. Optional postsubs inline substitutions are performed on the paragraph text.
5. The paragraph text is enveloped by the paragraph’s markup template and written to the output file.

### 28.3. Delimited Blocks

DelimitedBlock options values are:

sectionbody
  The block contents are processed as a SectionBody.
skip
  The block is treated as a comment (see CommentBlocks).

presubs, postsubs and filter entries are meaningless when sectionbody or skip options are set.

DelimitedBlock processing proceeds as follows:

1. Optional presubs substitutions are performed on the block contents.
2. If a filter is specified it is executed and the block’s contents piped to its standard input. The filter output replaces the block contents.
3. Optional postsubs substitutions are performed on the block contents.
4. The block contents is enveloped by the block’s markup template and written to the output file.

Attribute expansion is performed on the block filter command before it is executed, this is useful for passing arguments to the filter.

### 28.4. Lists

List behavior and syntax is determined by `[listdef*]` configuration file sections. The user can change existing list behavior and add new list types by editing configuration files.

List specific block definition notes:

type
  This is either bulleted,numbered,labeled or callout.
delimiter
  A Python regular expression that matches the first line of a list element entry. This expression can contain the named groups text (bulleted groups), index and text (numbered lists), label and text (labeled lists).
tags
  The `<name>` of the `[listtags-<name>]` configuration file section containing list markup tag definitions. The tag entries (list, entry, label, term, text) map the AsciiDoc list structure to backend markup; see the listtags sections in the AsciiDoc distributed backend `.conf` configuration files for examples.

### 28.5. Tables

Table behavior and syntax is determined by `[tabledef*]` and `[tabletags*]` configuration file sections. The user can change existing table behavior and add new table types by editing configuration files. The following `[tabledef*]` section entries generate table output markup elements:

comspec
  The table comspec tag definition.
headrow, footrow, bodyrow
  Table header, footer and body row tag definitions. headrow and footrow table definition entries default to bodyrow if they are undefined.
headdata, footdata, bodydata
  Table header, footer and body data tag definitions. headdata and footdata table definition entries default to bodydata if they are undefined.
paragraph
  If the paragraph tag is specified then blank lines in the cell data are treated as paragraph delimiters and marked up using this tag.

Table behavior is also influenced by the following `[miscellaneous]` configuration file entries:

pagewidth
  This integer value is the printable width of the output media. See table attributes.
pageunits
  The units of width in output markup width attribute values.

Table definition behavior

- The output markup generation is specifically designed to work with the HTML and CALS (DocBook) table models, but should be adaptable to most XML table schema.
- Table definitions can be “mixed in” from multiple cascading configuration files.
- New table definitions inherit the default table and table tags definitions (`[tabledef-default]` and `[tabletags-default]`) so you only need to override those conf file entries that require modification.

## 29. Filters

Filters are external shell commands used to process Paragraph and DelimitedBlock content; they are specified in configuration file Paragraph and DelimitedBlock definitions.

There’s nothing special about the filters, they’re just standard UNIX filters: they read text from the standard input, process it, and write to the standard output.

Attribute substitution is performed on the filter command prior to execution — attributes can be used to pass parameters from the AsciiDoc source document to the filter.

Filters can potentially generate unsafe output. Before installing a filter you should verify that it can’t be coerced into generating malicious output or exposing sensitive information.

### 29.1. Filter Search Paths

If the filter command does not specify a directory path then `asciidoc(1)` searches for the command:

- First it looks in the user’s `$HOME/.asciidoc/filters` directory.
- Next the `/etc/asciidoc/filters` directory is searched.
- Then it looks in the `asciidoc(1)` `./filters` directory.
- Finally it relies on the executing shell to search the environment search path (`$PATH`).

Sub-directories are also included in the searches — standard practice is to install each filter in it’s own sub-directory with the same name as the filter’s style definition. For example the music filter’s style name is music so it’s configuration and filter files are stored in the `filters/music` directory.

### 29.2. Filter Configuration Files

Filters are normally accompanied by a configuration file containing a Paragraph or DelimitedBlock definition along with corresponding markup templates.

While it is possible to create new Paragraph or DelimitedBlock definitions the preferred way to implement a filter is to add a style to the existing Paragraph and ListingBlock definitions (all filters shipped with AsciiDoc use this technique). The filter is applied to the paragraph or delimited block by preceding it with an attribute list: the first positional attribute is the style name, remaining attributes are normally filter specific parameters.

`asciidoc(1)` auto-loads all `.conf` files found in the filter search paths (see previous section).

### 29.3. Code Filter

AsciiDoc comes with a toy filter for highlighting source code keywords and comments. See also the `./filters/code/code-filter-readme.txt` file.

This filter primarily to demonstrate how to write a filter — it’s much to simplistic to be passed off as a code syntax highlighter. If you want a full featured multi-language highlighter use the Source Code Highlighter Filter.

    .Code filter example
    [code,python]
    ----------------------------------------------
    ''' A multi-line
        comment.'''
    def sub_word(mo):
        ''' Single line comment.'''
        word = mo.group('word')   # Inline comment
        if word in keywords[language]:
            return quote + word + quote
        else:
            return word
    ----------------------------------------------

Outputs:

Example 10. Code filter example

    ''' A multi-line
        comment.'''
    def sub_word(mo):
        ''' Single line comment.'''
        word = mo.group('word')   # Inline comment
        if word in keywords[language]:
            return quote + word + quote
        else:
            return word

### 29.4. Source Code Highlighter Filter

A source code highlighter filter can be found in the AsciiDoc distribution `./filters` directory.

### 29.5. Music Filter

A music filter is included in the distribution `./filters` directory. It translates music in LilyPond or ABC notation to standard Western classical notation in the form of a trimmed PNG image which is automatically inserted into the output document.

## 30. Converting DocBook to other file formats

DocBook files are validated, parsed and translated by a combination of applications collectively called a DocBook tool chain. The function of a tool chain is to read the DocBook markup (produced by AsciiDoc) and transform it to a presentation format (for example HTML, PDF, HTML Help, DVI, PostScript, LaTeX).

A wide range of user output format requirements coupled with a choice of available tools and stylesheets results in many valid tool chain combinations.

### 30.1. a2x Toolchain Wrapper

One of the biggest hurdles for new users is installing, configuring and using a DocBook XML toolchain. `a2x(1)` can help — it’s a toolchain wrapper command that will generate XHTML (chunked and unchunked), PDF, DVI, PS, LaTeX, man page, HTML Help and text file outputs from an AsciiDoc text file. `a2x(1)` does all the grunt work associated with generating and sequencing the toolchain commands and managing intermediate and output files. `a2x(1)` also optionally deploys admonition and navigation icons and a CSS stylesheet. See the `a2x(1)` man page for more details. All you need is xsltproc(1), DocBook XSL Stylesheets and optionally: dblatex or FOP (if you want PDF); `w3m(1)` or `lynx(1)` (if you want text).

The following examples generate `doc/source-highlight-filter.pdf` from the AsciiDoc `doc/source-highlight-filter.txt` source file. The first example uses `dblatex(1)` (the default PDF generator) the second example forces FOP to be used:

    $ a2x -f pdf doc/source-highlight-filter.txt
    $ a2x -f pdf --fop doc/source-highlight-filter.txt

See the `a2x(1)` man page for details.

Use the `--verbose` command-line option to view executed toolchain commands.

### 30.2. HTML generation

AsciiDoc produces nicely styled HTML directly without requiring a DocBook toolchain but there are also advantages in going the DocBook route:

- HTML from DocBook includes automatically generated indexes, tables of contents, footnotes, lists of figures and tables.
- DocBook toolchains can also (optionally) generate separate (chunked) linked HTML pages for each document section.
- Toolchain processing performs link and document validity checks.
- If the DocBook lang attribute is set then things like table of contents, revision history, figure and table captions and admonition captions will be output in the specified language (setting the AsciiDoc lang attribute sets the DocBook lang attribute).

On the other hand, HTML output directly from AsciiDoc is much faster, is easily customized and can be used in situations where there is no suitable DocBook toolchain (see the AsciiDoc website for example).

### 30.3. PDF generation

There are two commonly used tools to generate PDFs from DocBook, dblatex and FOP.

dblatex or FOP?

- dblatex is easier to install, there’s zero configuration required and no Java VM to install — it just works out of the box.
- dblatex source code highlighting and numbering is superb.
- dblatex is easier to use as it converts DocBook directly to PDF whereas before using FOP you have to convert DocBook to XML-FO using DocBook XSL Stylesheets.
- FOP is more feature complete (for example, callouts are processed inside literal layouts) and arguably produces nicer looking output.

### 30.4. HTML Help generation

1. Convert DocBook XML documents to HTML Help compiler source files using DocBook XSL Stylesheets and xsltproc(1).
2. Convert the HTML Help source (`.hhp` and `.html`) files to HTML Help (`.chm`) files using the Microsoft HTML Help Compiler.

### 30.5. Toolchain components summary

AsciiDoc
  Converts AsciiDoc (`.txt`) files to DocBook XML (`.xml`) files.
DocBook XSL Stylesheets
  These are a set of XSL stylesheets containing rules for converting DocBook XML documents to HTML, XSL-FO, manpage and HTML Help files. The stylesheets are used in conjunction with an XML parser such as xsltproc(1).
xsltproc
  An XML parser for applying XSLT stylesheets (in our case the DocBook XSL Stylesheets) to XML documents.
dblatex
  Generates PDF, DVI, PostScript and LaTeX formats directly from DocBook source via the intermediate LaTeX typesetting language —  uses DocBook XSL Stylesheets, xsltproc(1) and `latex(1)`.
FOP
  The Apache Formatting Objects Processor converts XSL-FO (`.fo`) files to PDF files. The XSL-FO files are generated from DocBook source files using DocBook XSL Stylesheets and xsltproc(1).
Microsoft Help Compiler
  The Microsoft HTML Help Compiler (`hhc.exe`) is a command-line tool that converts HTML Help source files to a single HTML Help (`.chm`) file. It runs on MS Windows platforms and can be downloaded from http://www.microsoft.com.

### 30.6. AsciiDoc dblatex configuration files

The AsciiDoc distribution `./dblatex` directory contains `asciidoc-dblatex.xsl` (customized XSL parameter settings) and `asciidoc-dblatex.sty` (customized LaTeX settings). These are examples of optional dblatex output customization and are used by `a2x(1)`.

### 30.7. AsciiDoc DocBook XSL Stylesheets drivers

You will have noticed that the distributed HTML and HTML Help documentation files (for example `./doc/asciidoc.html`) are not the plain outputs produced using the default DocBook XSL Stylesheets configuration. This is because they have been processed using customized DocBook XSL Stylesheets along with (in the case of HTML outputs) the custom `./stylesheets/docbook.css` CSS stylesheet.

You’ll find the customized DocBook XSL drivers along with additional documentation in the distribution `./docbook-xsl` directory. The examples that follow are executed from the distribution documentation (`./doc`) directory.

`common.xsl`
  Shared driver parameters. This file is not used directly but is included in all the following drivers.
`chunked.xsl`

  Generate chunked XHTML (separate HTML pages for each document section) in the `./doc/chunked` directory. For example:

      $ python ../asciidoc.py -b docbook asciidoc.txt
      $ xsltproc --nonet ../docbook-xsl/chunked.xsl asciidoc.xml

`fo.xsl`

  Generate XSL Formatting Object (`.fo`) files for subsequent PDF file generation using FOP. For example:

      $ python ../asciidoc.py -b docbook article.txt
      $ xsltproc --nonet ../docbook-xsl/fo.xsl article.xml > article.fo
      $ fop.sh article.fo article.pdf

`htmlhelp.xsl`

  Generate Microsoft HTML Help source files for the MS HTML Help Compiler in the `./doc/htmlhelp` directory. This example is run on MS Windows from a Cygwin shell prompt:

      $ python ../asciidoc.py -b docbook asciidoc.txt
      $ xsltproc --nonet ../docbook-xsl/htmlhelp.xsl asciidoc.xml
      $ c:/Program\ Files/HTML\ Help\ Workshop/hhc.exe htmlhelp.hhp

`manpage.xsl`

  Generate a `roff(1)` format UNIX man page from a DocBook XML refentry document. This example generates an `asciidoc.1` man page file:

      $ python ../asciidoc.py -d manpage -b docbook asciidoc.1.txt
      $ xsltproc --nonet ../docbook-xsl/manpage.xsl asciidoc.1.xml

`xhtml.xsl`

  Convert a DocBook XML file to a single XHTML file. For example:

      $ python ../asciidoc.py -b docbook asciidoc.txt
      $ xsltproc --nonet ../docbook-xsl/xhtml.xsl asciidoc.xml > asciidoc.html

If you want to see how the complete documentation set is processed take a look at the A-A-P script `./doc/main.aap`.

## 31. Generating Plain Text Files

AsciiDoc does not have a text backend (for most purposes AsciiDoc source text is fine), however you can convert AsciiDoc text files to formatted text using the AsciiDoc `a2x(1)` toolchain wrapper utility.

## 32. XML and Character Sets

The default XML character set `UTF-8` is used when AsciiDoc generates DocBook files but this can be changed by setting the `xmldecl` entry in the `[attributes]` section of the `docbook.conf` file or by composing your own configuration file `[header]` section).

If you get an undefined entity error when processing DocBook files you’ll may find that you’ve used an undefined HTML character entity. An easy (although inelegant) fix is to use the character’s character code instead of its symbolic name (for example use `&#160;` instead of `&nbsp;`).

If your system has been configured with an XML catalog you may find a number of entity sets are already automatically included.

### 32.1. PDF Fonts

The Adobe PDF Specification states that the following 14 fonts should be available to every PDF reader: Helvetica (normal, bold, italic, bold italic), Times (normal, bold, italic, bold italic), Courier (normal, bold, italic, bold italic), Symbol and ZapfDingbats. Non-standard fonts should be embedded in the distributed document.

## 33. Help Commands

The `asciidoc(1)` command has a `--help` option which prints help topics to stdout. The default topic summarizes `asciidoc(1)` usage:

    $ asciidoc --help

To print a list of help topics:

    $ asciidoc --help=topics

To print a help topic specify the topic name as a command argument. Help topic names can be shortened so long as they are not ambiguous. Examples:

    $ asciidoc --help=manpage
    $ asciidoc -hm              # Short version of previous example.
    $ asciidoc --help=syntax
    $ asciidoc -hs              # Short version of previous example.

### 33.1. Customizing Help

To change, delete or add your own help topics edit a help configuration file. The help file name `help-<lang>.conf` is based on the setting of the `lang` attribute, it defaults to `help.conf` (English). The help file location will depend on whether you want the topics to apply to all users or just the current user.

The help topic files have the same named section format as other configuration files. The `help.conf` files are stored in the same locations and loaded in the same order as other configuration files.

When the `--help` command-line option is specified AsciiDoc loads the appropriate help files and then prints the contents of the section whose name matches the help topic name. If a topic name is not specified `default` is used. You don’t need to specify the whole help topic name on the command-line, just enough letters to ensure it’s not ambiguous. If a matching help file section is not found a list of available topics is printed.

## 34. Tips and Tricks

### 34.1. Know Your Editor

Writing AsciiDoc documents will be a whole lot more pleasant if you know your favorite text editor. Learn how to indent and reformat text blocks, paragraphs, lists and sentences. Tips for vim users follow.

### 34.2. Vim Commands for Formatting AsciiDoc

#### 34.2.1. Text Wrap Paragraphs

Use the vim `:gq` command to reformat paragraphs. Setting the textwidth sets the right text wrap margin; for example:

    :set textwidth=70

To reformat a paragraph:

1. Position the cursor at the start of the paragraph.
2. Type `gq}`.

Execute `:help gq` command to read about the vim gq command.

Assign the `gq}` command to the Q key with the `nnoremap Q gq}` command or put it in your `~/.vimrc` file to so it’s always available (see the Example `~/.vimrc` file). Put `set` commands in your `~/.vimrc` file so you don’t have to enter them manually. The Vim website (http://www.vim.org) has a wealth of resources, including scripts for automated spell checking and ASCII Art drawing.

#### 34.2.2. Format Lists

The `gq` command can also be used to format bulleted, numbered and callout lists. First you need to set the `comments`, `formatoptions` and `formatlistpat` (see the Example `~/.vimrc` file).

Now you can format simple lists that use dash, asterisk, period and plus bullets along with numbered ordered lists:

1. Position the cursor at the start of the list.
2. Type `gq}`.

#### 34.2.3. Indent Paragraphs

Indent whole paragraphs by indenting the fist line with the desired indent and then executing the `gq}` command.

#### 34.2.4. Example `~/.vimrc` File

    " Show tabs and trailing characters.
    set listchars=tab:»·,trail:·
    set list

    " Don't highlight searched text.
    highlight clear Search

    " Don't move to matched text while search pattern is being entered.
    set noincsearch

    " Reformat paragraphs and list.
    nnoremap R gq}

    " Delete trailing white space and Dos-returns and to expand tabs to spaces.
    nnoremap S :set et<CR>:retab!<CR>:%s/[\r \t]\+$//<CR>

    autocmd BufRead,BufNewFile *.txt,README,TODO,CHANGELOG,NOTES
            \ setlocal autoindent expandtab tabstop=8 softtabstop=2 shiftwidth=2 filetype=asciidoc
            \ textwidth=70 wrap formatoptions=tcqn
            \ formatlistpat=^\\s*\\d\\+\\.\\s\\+\\\\|^\\s*<\\d\\+>\\s\\+\\\\|^\\s*[a-zA-Z.]\\.\\s\\+\\\\|^\\s*[ivxIVX]\\+\\.\\s\\+
            \ comments=s1:/*,ex:*/,://,b:#,:%,:XCOMM,fb:-,fb:*,fb:+,fb:.,fb:>

### 34.3. Troubleshooting

- The `asciidoc(1)` `-v` (`--verbose`) command-line option displays the order of configuration file loading and warns of potential configuration file problems.
- Not all valid AsciiDoc documents produce valid backend markup. Read the AsciiDoc Backends section if AsciiDoc output is rejected as non-conformant by a backend processor.

### 34.4. Gotchas

Incorrect character encoding
  If you get an error message like `'UTF-8' codec can't decode ...` then you source file contains invalid UTF-8 characters — set the AsciiDoc encoding attribute for the correct character set (typically ISO-8859-1 (Latin-1) for European languages).
Invalid output

  AsciiDoc attempts to validate the input AsciiDoc source but makes no attempt to validate the output markup, it leaves that to external tools such as `xmllint(1)` (integrated into `a2x(1)`). Backend validation cannot be hardcoded into AsciiDoc because backends are dynamically configured. The following example generates valid HTML but invalid DocBook (the DocBook `literal` element cannot contain an `emphasis` element):

      +monospaced text with an _emphasized_ word+

Misinterpreted text formatting

  You can suppress markup expansion by placing a backslash character immediately in front of the element. The following example suppresses inline monospaced formatting:

      \+1 for C++.

Overlapping text formatting

  Overlapping text formatting will generate illegal overlapping markup tags which will result in downstream XML parsing errors. Here’s an example:

      Some *strong markup _that overlaps* emphasized markup_.

Ambiguous underlines
  A DelimitedBlock can immediately follow paragraph without an intervening blank line, but be careful, a single line paragraph underline may be misinterpreted as a section title underline resulting in a “closing block delimiter expected” error.
Ambiguous ordered list items

  Lines beginning with numbers at the end of sentences will be interpreted as ordered list items. The following example (incorrectly) begins a new list with item number 1999:

      He was last sighted in
      1999. Since then things have moved on.

  The list item out of sequence warning makes it unlikely that this problem will go unnoticed.

Special characters in attribute values

  Special character substitution precedes attribute substitution so if attribute values contain special characters you may, depending on the substitution context, need to escape the special characters yourself. For example:

      $ asciidoc -a 'corpname=Bill &amp; Ben Inc.' mydoc.txt

Macro attribute lists

  If named attribute list entries are present then all string attribute values must be quoted. For example:

      ["Desktop screenshot",width=32]

### 34.5. Combining separate documents

You have a number of stand-alone AsciiDoc documents that you want to process as a single document. Simply processing them with a series of `include` macros won’t work because the documents contain (level 0) document titles. The solution is to create a top level wrapper document that redefines the document underlines, pushing them down one level. For example `combined.txt`:

    :titles.underlines: "__","==","--","~~","^^"

    Combined Document Title
    _______________________

    include::document1.txt[]

    include::document2.txt[]

    include::document3.txt[]

The document titles in the included documents will now be processed as level 1 section titles.

- Put a blank line between the `include` macro lines to ensure the title of the included document is not seen as part of the last paragraph of the previous document.
- You won’t want document Headers (Author and Revision lines) in the included files — conditionally exclude them if they are necessary for stand-alone processing.

### 34.6. Processing document sections separately

You have divided your AsciiDoc document into separate files (one per top level section) which are combined and processed with the following top level document:

    Combined Document Title
    =======================
    Joe Bloggs
    v1.0, 12-Aug-03

    include::section1.txt[]

    include::section2.txt[]

    include::section3.txt[]

You also want to process the section files as separate documents. This is easy because `asciidoc(1)` will quite happily process `section1.txt`, `section2.txt` and `section3.txt` separately — the resulting output documents contain the section but have no document title.

Use the `-s` (`--no-header-footer`) command-line option to suppress header and footer output, this is useful if the processed output is to be included in another file. For example:

    $ asciidoc -s -b docbook section1.txt

### 34.7. Processing document snippets

`asciidoc(1)` can be used as a filter, so you can pipe chunks of text through it. For example:

    $ echo 'Hello *World!*' | asciidoc -s -
    <div class="paragraph"><p>Hello <strong>World!</strong></p></div>

### 34.8. Badges in HTML page footers

See the `[footer]` section in the AsciiDoc distribution `xhtml11.conf` configuration file.

### 34.9. Pretty printing AsciiDoc output

If the indentation and layout of the `asciidoc(1)` output is not to your liking you can:

1. Change the indentation and layout of configuration file markup template sections. The `{empty}` glossary entry is useful for outputting trailing blank lines in markup templates.

2. Use Dave Raggett’s HTML Tidy program to tidy `asciidoc(1)` output. Example:

       $ asciidoc -b docbook -o - mydoc.txt | tidy -indent -xml >mydoc.xml

3. Use the `xmllint(1)` format option. Example:

       $ xmllint --format mydoc.xml

### 34.10. Supporting minor DocBook DTD variations

The conditional inclusion of DocBook SGML markup at the end of the distribution `docbook.conf` file illustrates how to support minor DTD variations. The included sections override corresponding entries from preceding sections.

### 34.11. Shipping stand-alone AsciiDoc source

Reproducing presentation documents from someone else’s source has one major problem: unless your configuration files are the same as the creator’s you won’t get the same output.

The solution is to create a single backend specific configuration file using the `asciidoc(1)` `-c` (`--dump-conf`) command-line option. You then ship this file along with the AsciiDoc source document plus the `asciidoc.py` script. The only end user requirement is that they have Python installed (and of course that they consider you a trusted source). This example creates a composite HTML configuration file for `mydoc.txt`:

    $ asciidoc -cb xhtml11 mydoc.txt > mydoc-xhtml11.conf

Ship `mydoc.txt`, `mydoc-html.conf`, and `asciidoc.py`. With these three files (and a Python interpreter) the recipient can regenerate the HMTL output:

    $ ./asciidoc.py -eb xhtml11 mydoc.txt

The `-e` (`--no-conf`) option excludes the use of implicit configuration files, ensuring that only entries from the `mydoc-html.conf` configuration are used.

### 34.12. Inserting blank space

Adjust your style sheets to add the correct separation between block elements. Inserting blank paragraphs containing a single non-breaking space character `{nbsp}` works but is an ad hoc solution compared to using style sheets.

### 34.13. Closing open sections

You can close off section tags up to level `N` by calling the `eval::[Section.setlevel(N)]` system macro. This is useful if you want to include a section composed of raw markup. The following example includes a DocBook glossary division at the top section level (level 0):

    ifdef::backend-docbook[]

    eval::[Section.setlevel(0)]

    +++++++++++++++++++++++++++++++
    <glossary>
      <title>Glossary</title>
      <glossdiv>
      ...
      </glossdiv>
    </glossary>
    +++++++++++++++++++++++++++++++
    endif::backend-docbook[]

### 34.14. Validating output files

Use `xmllint(1)` to check the AsciiDoc generated markup is both well formed and valid. Here are some examples:

    $ xmllint --nonet --noout --valid docbook-file.xml
    $ xmllint --nonet --noout --valid xhtml11-file.html
    $ xmllint --nonet --noout --valid --html html4-file.html

The `--valid` option checks the file is valid against the document type’s DTD, if the DTD is not installed in your system’s catalog then it will be fetched from its Internet location. If you omit the `--valid` option the document will only be checked that it is well formed.

## Glossary

Block element

  An AsciiDoc block element is a document entity composed of one or more whole lines of text.

Inline element

  AsciiDoc inline elements occur within block element textual content, they perform formatting and substitution tasks.

Formal element

  An AsciiDoc block element that has a BlockTitle. Formal elements are normally listed in front or back matter, for example lists of tables, examples and figures.

Verbatim element

  The word verbatim indicates that white space and line breaks in the source document are to be preserved in the output document.

## A. Migration Notes

### A.1. Version 7 to version 8

- A new set of quotes has been introduced which may match inline text in existing documents — if they do you’ll need to escape the matched text with backslashes.
- The index entry inline macro syntax has changed — if your documents include indexes you may need to edit them.
- Replaced `a2x(1)` `--no-icons` and `--no-copy` options with their negated equivalents: `--icons` and `--copy` respectively. The default behavior has also changed — the use of icons and copying of icon and CSS files must be specified explicitly with the `--icons` and `--copy` options.

The rationale for the changes can be found in the AsciiDoc `CHANGELOG`.

If you want to disable unconstrained quotes, the new alternative constrained quotes syntax and the new index entry syntax then you can define the attribute `asciidoc7compatible` (for example by using the `-a asciidoc7compatible` command-line option).

## B. Packager Notes

Read the `README` and `INSTALL` files (in the distribution root directory) for install prerequisites and procedures. The distribution `Makefile.in` (used by `configure` to generate the `Makefile`) is the canonical installation procedure.

## C. AsciiDoc Safe Mode

AsciiDoc safe mode skips potentially dangerous sections in AsciiDoc source files by inhibiting the execution of arbitrary code or the inclusion of arbitrary files.

The safe mode is enabled by default and can only be disabled using the `asciidoc(1)` `--unsafe` command-line option.

Safe mode constraints

- `eval`, `sys` and `sys2` executable attributes and block macros are not executed.
- `include::<filename>[]` and `include1::<filename>[]` block macro files must reside inside the parent file’s directory.
- `{include:<filename>}` executable attribute files must reside inside the source document directory.
- Passthrough Blocks are dropped.

The safe mode is not designed to protect against unsafe AsciiDoc configuration files. Be especially careful when: Implementing filters. Implementing elements that don’t escape special characters. Accepting configuration files from untrusted sources.

## D. Using AsciiDoc with non-English Languages

AsciiDoc can process UTF-8 character sets but there are some things you need to be aware of:

- If you are generating output documents using a DocBook toolchain then you should set the AsciiDoc `lang` attribute to the appropriate language (it defaults to `en` (English)). This will ensure things like table of contents, revision history, figure and table captions and admonition captions are output in the specified language. For example:

      $ a2x -a lang=es doc/article.txt

- If you are outputting html or xhtml directly from `asciidoc(1)` you’ll need to set the various `*_caption` attributes to match your target language (see the list of captions and titles in the `[attributes]` section of the default `asciidoc.conf` file). The easiest way is to create a language `.conf` file (see the example `lang-es.conf` file that comes with the AsciiDoc distribution).
- `asciidoc(1)` automatically loads configuration files named like `lang-<lang>.conf` where `<lang>` is a two letter language code that matches the current AsciiDoc `lang` attribute. See also Configuration File Names and Locations.
- Some character sets display double-width characters (for example Japanese). As far as title underlines are concerned they should be treated as single character. If you think this looks untidy so you may prefer to use the single line title format.

## E. Vim Syntax Highlighter

The AsciiDoc `./vim/` distribution directory contains Vim syntax highlighter and filetype detection scripts for AsciiDoc. Syntax highlighting makes it much easier to spot AsciiDoc syntax errors.

If Vim is installed on your system the AsciiDoc installer (`install.sh`) will automatically install the vim scripts in the Vim global configuration directory (`/etc/vim`).

You can also turn on syntax highlighting by adding the following line to the end of you AsciiDoc source files:

    // vim: set syntax=asciidoc:

Dag Wieers has implemented an alternative Vim syntax file for AsciiDoc which can be found here http://svn.rpmforge.net/svn/trunk/tools/asciidoc-vim/.

Emacs users: The *Nix Power Tools project has released an AsciiDoc syntax highlighter for emacs.

### E.1. Limitations

The current implementation does a reasonable job but on occasions gets things wrong. This list of limitations also discusses how to work around the problems:

- Indented lists with preceding blank lines are sometimes mistaken for literal (indented) paragraphs. You can work around this by deleting the preceding blank line, or inserting a space in the preceding blank lines, or putting a list continuation character (`+`) in the preceding blank line.
- Nested quoted text formatting is highlighted according to the outer format.
- If a closing block delimiter is not preceded by a blank line it is sometimes mistaken for a title underline. A workaround is to insert a blank line before the closing delimiter.
- If a list block delimiter is mistaken for a title underline precede it with a blank line.

- Lines within a paragraph beginning with a period will be highlighted as block titles. For example:

      .chm file.

  To work around this restriction move the last word of the previous line to the start of the current (although words starting with a period should probably be quoted monospace which would also get around the problem).

Sometimes incorrect highlighting is caused by preceding lines that appear blank but contain white space characters — setting your editor options so that white space characters are visible is a good idea.

## F. Attribute Options

Here is the list of predefined attribute list options:

Option | Backends | AsciiDoc Elements | Description
--- | --- | --- | ---
compact | docbook, xhtml11 | bulleted list, numbered list | Minimizes vertical space in the list
strong | xhtml11,html4 | labeled lists | Emboldens label text.
footer | docbook, xhtml11, html4 | table | The last row of the table is rendered as a footer.
header | docbook, xhtml11, html4 | table | The first row of the table is rendered as a header.
autowidth | xhtml11,html4 | table | The column widths are determined by the browser, not the AsciiDoc cols attribute. If there is no width attribute the table width is also left up to the browser.
breakable, unbreakable | docbook (XSL/FO) | table | The breakable options allows the table to break across page boundaries (the default behavior); unbreakable attempts to keep the table together on a single page. If neither option is specified the default XSL stylesheet behavior prevails.
pgwide | docbook (XSL/FO) | table, block image, horizontal labeled list | Specifies that the element should be rendered across the full text width of the page irrespective of the current indentation.

## G. Diagnostics

The `asciidoc(1)` `--verbose` command-line option prints additional information to stderr: files processed, filters processed, warnings, system attribute evaluation.

A special attribute named trace controls the output of diagnostic information. If the trace attribute is defined then element-by-element diagnostic messages detailing output markup generation are printed to stderr. The trace attribute can be set on the command-line or from within the document using Attribute Entries (the latter allows tracing to be confined to specific portions of the document).

- Trace messages consist of a descriptive name followed by the related markup.
- The trace message is only printed if the trace attribute value matches the start of the trace name. The trace attribute value can be any Python regular expression.
- A blank trace value matches all trace names and all trace messages will be printed (this can result in large amounts of output if applied to the whole document).

- In the case of inline substitutions:

  - The text before and after the substitution are printed delineated by `<<<` and `>>>` delimiters.
  - The message is only printed if a substitution is made.
  - The subs trace value is an alias for all inline substitutions.

Command-line examples:

1. Trace the entire document.

       $ asciidoc -a trace mydoc.txt

2. Trace messages whose names start with `quotes` or `macros`:

       $ asciidoc -a 'trace=quotes|macros'  mydoc.txt

3. Print the first line of all trace messages:

       $ asciidoc -a trace mydoc.txt 2>&1 | grep ^TRACE:

Attribute Entry examples:

1. Begin printing all trace messages:

       :trace:

2. Print only matched trace messages:

       :trace: quotes|macros

3. Turn trace messages off:

       :trace!:

[1] This is a rough structural guide, not a rigorous syntax definition

[2] An example footnote.

[3] Second footnote

[4] The existence of a `{revisionhistory}` attribute causes a revision history file (if it exists) to be included in DocBook outputs. If a file named like `{docname}-revhistory.xml` exists in the document’s directory then it will be added verbatim to the DocBook header (see the `./doc/asciidoc-revhistory.xml` example that comes with the AsciiDoc distribution).

[5] Conditional inclusion using `ifdef` and `ifndef` macros differs from attribute conditional inclusion in that the former occurs when the file is read while the latter occurs when the contents are written.