sed & awk, 2nd Edition

Coding Index Entries

This section describes the coding of index entries in the document file. We use the .XX macro for placing index entries in a file. The simplest case is:

.XX "entry"

If the entry consists of primary and secondary sort keys, then we can code it as:

.XX "primary, secondary"

A comma delimits the two keys. We also have a .XN macro for generating “See” references without a page number. It is specified as:

.XN "entry (See anotherEntry)"

While these coding forms continue to work as they have, masterindex provides greater flexibility by allowing three levels of keys: primary, secondary, and tertiary. You’d specify the entry like so:

.XX "primary: secondary; tertiary"

Note that the comma is not used as a delimiter. A colon delimits the primary and secondary entry; the semicolon delimits the secondary and tertiary entry. This means that commas can be a part of a key using this syntax. Don’t worry, though, you can continue to use a comma to delimit the primary and secondary keys. (Be aware that the first comma in a line is converted to a colon, if no colon delimiter is found.) I’d recommend that new books be coded using the above syntax, even if you are only specifying a primary and secondary key.

Another feature is automatic rotation of primary and secondary keys if a tilde (~) is used as the delimiter. So the following entry:

.XX "cat~command"

is equivalent to the following two entries:

.XX "cat command"
.XX "command: cat"

You can think of the secondary key as a classification (command, ...