After the section describing roles that create cross-references to C-language constructs, the Dev Guide says this, "The following roles don’t do anything special except formatting the text in a different style."

http://hg.python.org/devguide/file/f518f23d06d5/documenting.rst#l984

However, some of the roles following in that section do do special things other than formatting.  For example--

envvar
    An environment variable. Index entries are generated.

keyword
    The name of a Python keyword. Using this role will generate a link to the documentation of the keyword....
    
The description should be changed, or better yet, the roles that do something special should be moved to a different section.