Modules can be marked obsolete. This means that the problems they fix
don't occur any more on the platforms that are reasonable porting targets
now. gnulib-tool warns when obsolete modules are mentioned on the
command line, and by default ignores dependencies from modules to obsolete
modules. When you pass the option --with-obsolete to
gnulib-tool, dependencies to obsolete modules will be included,
however, unless blocked through an --avoid option. This option
is useful if your package should be portable even to very old platforms.
In order to mark a module obsolete, you need to add this to the module description:
Status:
obsolete
Notice:
This module is obsolete.