listdirectives directive is supplied by the listdirectives plugin.
This directive generates a list of available directives.
There is one optional keyword argument,
generated. Normally the
listdirectives directive will list all built in directives and directives
directly registered by plugins. With this keyword,
also list directives generated later. For example, all shortcuts are
directives generated in turn by the
shortcut directive. They will only
be listed if the
generated argument is supplied.
This extended list is often quite long, and often contains many undocumented directives.