What does the `X` suffix mean in namespaces?

Question

There are Perl module names like Moose and MooseX or DBI and DBIx or Catalyst and CatalystX or Mojo and MojoX or PPI and PPIx, etc.

What does the X suffix mean there?

Answer 1

eXtension, pretty much. It is just a convention to add features to a code base without stomping on the actual namespace or trespassing. DBIx means it's related to but not a part of DBI, for example.