Description:

Module::CoreList contains the hash of hashes
Module::CoreList::version, this is keyed on perl version as indicated
in $]. The second level hash is module => version pairs.

Note, it is possible for the version of a module to be unspecified,
whereby the value is undef, so use "exists $version{$foo}{$bar}" if
that's what you're testing for.

It also contains Module::CoreList::released hash, which has ISO
formatted versions of the release dates, as gleaned from perlhist.

New, in 1.96 is also the Module::CoreList::families hash, which
clusters known perl releases by their major versions.

In 2.01 Module::CoreList::patchlevel contains the branch and patchlevel
corresponding to the specified perl version in the Perforce repository where
the perl sources are kept.