# 15 Definition Commands

The `@deffn` command and the other definition commands enable you to describe functions, variables, macros, commands, user options, special forms and other such artifacts in a uniform format.

In the Info file, a definition causes the entity category—‘Function’, ‘Variable’, or whatever—to appear at the beginning of the first line of the definition, followed by the entity’s name and arguments. In the printed manual, the command causes TeX to print the entity’s name and its arguments on the left margin and print the category next to the right margin. In both output formats, the body of the definition is indented. Also, the name of the entity is entered into the appropriate index: `@deffn` enters the name into the index of functions, `@defvr` enters it into the index of variables, and so on.

A manual need not and should not contain more than one definition for a given name. An appendix containing a summary should use `@table` rather than the definition commands.

This document was generated on a sunny day using texi2html.