# SGML and Information Manager Document Structure

This chapter introduces, briefly and at a very high-level, some SGML concepts and terminology as they relate to the Information Manager’s on-line documentation model. It also discusses how the Information Manager organizes SGML information for on-line presentation. It includes these topics:

- How SGML Structures Information

- How the Information Manager Organizes On-line Information

Go directly to Preparing to Build if you are interested in learning about the build process.

## How SGML Structures Information

Standard Generalized Markup Language (SGML) is an international standard for defining the structure of information in a document. It does this by identifying the elements of a document and then describing the relationships of these elements to each other using a formal markup language.

Elements are the logical building blocks of an SGML document such as its chapters, paragraphs, tables, graphics, and so forth. As described in the SGML standard (ISO 8879): “A document is a logical construct that contains a document element, the top node of a tree of elements that make up the document’s content.”

This hierarchy of logical elements is itself made up of a collection of physical entities, which can include files, parts of files, graphics, and other data. These physical entities are pulled together during the build process into the logical structure defined by the document type definition (DTD) for a given document.

The DTD is described briefly below.

### Document Type Definition

The rules that govern the types of elements that can be contained in a given document and their order and frequency are defined in a special SGML document called a Document Type Definition (DTD).

The DTD contains the markup rules that pertain to a class of documents, including the list of allowable elements that can be used in documents of a given type.

For example, the DTD may stipulate that a document must consist of at least one chapter, a summary abstract, and an index.

It may further define the relationships and the content of these elements, stating, for example, that chapters must start with a chapter title followed by one or more paragraphs, each of which can contain numbered lists, bulleted lists, tables, graphics, and so forth.

Through this process of defining the elements that comprise a given document type and the attributes that an element can have, the DTD dictates the structure of the document.

For more information about the SGML standard, see Related Documentation.

## How Information Manager Organizes On-line Information

When you view on-line information through the Information Manager Book List window, you are looking at a collection of one or more bookcases of books about related topics. This collection is referred to as an information library. Each bookcase contains one or more books.

This section describes the structure of on-line information in the Information Manager. The figure On-line Information Structure depicts the Information Manager’s library structure.

### On-line Information Structure

An Information Manager information library (infolib) is created from SGML-conforming documents by a set of software tools called the Information System Toolkit. The SGML documents contain all of the text, tables, graphics, and other related elements that make up the books in each of the bookcases. The Information Manager tools take the SGML input and organize it internally into a hypertext-linked database that makes retrieval of specific pieces of information in the library very efficient.

Each book in an Information Manager information library contains a hypertext table of contents (TOC) and one or more sections. The hypertext TOC
is the entry point into an on-line book in the Information Manager. The TOC describes the structure of the document and acts as an interactive electronic map to help you navigate through the document to find specific information contained in the section(s). To “move” to a section within the on-line document body, you simply select the desired section title in the TOC.

Sections are the smallest units of information in an Information Manager on-line book. They consist primarily of text but can also include graphics and tables.

Information Manager “connects” book sections to the TOC through the use of hypertext links
. Each entry in the TOC contains a unique hypertext reference, whose value maps to a section in the on-line document.

These TOC hypertext links provide many of the advanced document navigation features found in the Information Manager, including the collapsible book list, the graphical location map, and the printing hierarchy.

### On-line Information Hierarchy

The on-line information hierarchy, as structured in the Information Manager, consists of:

Information library

- A collection of bookcases.

Bookcase

- A collection of style sheets and books. The bookcase also contains a full-text search index constructed by the Toolkit.

Book

- One or more sections organized under a hypertext TOC.

Section

- The smallest unit of information in a book. Each section is referenced in the TOC and is viewable in one reading window of the browser.

#### On-line Information Structure

In order for the tools in the Information System Toolkit to structure your documents correctly, you must apply Information Manager architectural forms to your documents’ DTDs. Applying Information Manager architectural forms to your DTD does not invalidate your existing document instances.

The DTDs that are shipped with Information Manager— `dtinfoBook.dtd`, `dtinfoTOC.dtd`, `dtinfoStyle.dtd`, and `docbook.dtd`— already contain these architectural forms.

See Using Architectural Forms for instructions on applying the Information Manager architectural forms to your documents’ DTDs.

For related information, see:

- Required Files

- Build Considerations