a8xd: document color scheme.

1 files changed, 58 insertions, 12 deletions

diff --git a/a8xd.rst b/a8xd.rst
index 71d3855..22a85a9 100644
--- a/a8xd.rst
+++ b/a8xd.rst
@@ -23,18 +23,8 @@ The ATASCII codes are converted to UTF-8, in the same way as
 **a8cat**\(1). Codes with the high bit set are displayed in inverse
 video, using ANSI/VT-100 escape sequences.
 
-By default, the output is colorized:
-
-  - Normal characters are green. This includes alphanumerics, spaces, and
-    punctuation.
-
-  - Codes **$00** (null, or ATASCII heart) and **$9B** (EOL) are red.
-
-  - Control characters are yellow. This includes codes **$01** to **$1F**
-    (control + letters/punctuation, escape, and arrow keys), **$60**, **$7B**, **$7D**
-    (clear screen), **$7E** (backspace), and **$7F** (tab).
-
-The colors and inverse rendering apply to both the ATASCII and hex bytes.
+By default, the output is colorized (see **COLORS**, below). The
+colors and inverse rendering apply to both the ATASCII and hex bytes.
 
 Without *infile*, or if *infile* is **-**, **a8xd** reads from standard input.
 
@@ -93,6 +83,62 @@ OPTIONS
 **--version**
   Show version number and exit.
 
+COLORS
+======
+
+The default color scheme is:
+
+  - Non-control characters are green. This includes alphanumerics, spaces, and
+    punctuation. These are the characters that ATASCII has in common with
+    ASCII.
+
+  - Graphics characters are yellow. This includes **$01** to **$1a** (the
+    alphabet, with the Control key held down), **$60** (the diamond), and
+    **$7b** (the spade).
+
+  - Codes **$00** (null, or ATASCII heart) and **$9B** (EOL) are red. These
+    characters are used as delimiters, so it makes sense for them to
+    stand out.
+
+  - Cursor control characters are purple. These are characters that perform
+    some action when printed to the *E:* device. These are:
+
+      **$1b**
+        Escape.
+
+      **$1c** through **$1f**
+        Cursor movement (up/down/left/right arrows).
+
+      **$7d**
+        Clear screen.
+
+      **$7e**
+        Backspace.
+
+      **$7f**
+        Tab.
+
+      **$9c**
+        Delete line.
+
+      **$9d**
+        Insert line.
+
+      **$9e**
+        Clear tab stop.
+
+      **$9f**
+        Set tab stop.
+
+      **$fd**
+        Bell.
+
+      **$fe**
+        Delete character.
+
+      **$ff**
+        Insert character.
+
 NOTES
 =====