If this directory exists, menu entries for the single metapackages can
be provided here.  The files should have the same name as the files in
the tasks directory and ideally each single task should have its own
menu.

See for instance Debian Med packages.

In general a metapackage should provide a menu for every dependent
package.  This menu entry should either point to a package executable
(perhaps with some special hints assigned) or to a pager call which
provides some extra information how the special package can be used.
For instance this can be done via text files
/usr/share/doc/_BLEND_task1/deppkg1.txt (see Debian Med).

The idea is to provide a special _BLEND_ menu with the relevant parts
for the users of the _BLEND_.

At install time the existing dependencies are checked for their menu
entries.  These are taken over into the user menu.  If the metapackage
maintainer wants to override this entry he is able to provide
menu/<task>/<dep>.menu files.  If there is no reasonable menu entry
for a package extra documentation can be provided which can be viewed
via menu entries.  This can either be given as plain text files
menu/<task>/<dep>.txt or HTML files menu/<task>/<dep>.html.  The
created menu entry calls sensible-pager or sensible-browser,
respectively.
