Node:Tags, Next:Checking, Previous:Cross-refs, Up:Advanced Info

Tags Tables for Info Files

You can speed up the access to nodes of a large Info file by giving it a tags table. Unlike the tags table for a program, the tags table for an Info file lives inside the file itself and is used automatically whenever Info reads in the file.

To make a tags table, go to a node in the file using Emacs Info mode and type M-x Info-tagify. Then you must use C-x C-s to save the file. Info files produced by the makeinfo command that is part of the Texinfo package always have tags tables to begin with.

Once the Info file has a tags table, you must make certain it is up to date. If you edit an Info file directly (as opposed to editing its Texinfo source), and, as a result of deletion of text, any node moves back more than a thousand characters in the file from the position recorded in the tags table, Info will no longer be able to find that node. To update the tags table, use the Info-tagify command again.

An Info file tags table appears at the end of the file and looks like this:

^_^L
Tag Table:
File: info, Node: Cross-refs^?21419
File: info,  Node: Tags^?22145
^_
End Tag Table

Note that it contains one line per node, and this line contains the beginning of the node's header (ending just after the node name), a DEL character, and the character position in the file of the beginning of the node.