Here are the commands for defining variables and similar entities:
@defvr category name ¶The @defvr command is a general definition command for
something like a variable—an entity that records a value. You must
choose a term to describe the category of entity being defined; for
example, “Variable” could be used if the entity is a variable.
Write the @defvr command at the beginning of a line and
follow it on the same line by the category of the entity and the
name of the entity.
We recommend capitalizing the category name like a title. If the name of the category contains spaces, as in the name “User Option”, enclose it in braces. Otherwise, the second word will be mistaken for the name of the entity. For example,
@defvr {User Option} fill-column
This buffer-local variable specifies
the maximum width of filled lines.
...
@end defvr
Terminate the definition with @end defvr on a line of its
own.
@defvr creates an entry in the index of variables for name.
@defvar name ¶The @defvar command is the definition command for variables.
@defvar is equivalent to ‘@defvr Variable
…’.
For example:
@defvar kill-ring ... @end defvar
@defvar creates an entry in the index of variables for
name.
@defopt name ¶The @defopt command is the definition command for user
options, i.e., variables intended for users to change according to
taste; Emacs has many such (see Variables in The GNU Emacs
Manual). @defopt is equivalent to ‘@defvr {User
Option} …’.