Pdbsql provides three samba passdb backend modules: pdb_mysql, pdb_pgsql, and pdb_multi. pdb_mysql is a MySQL passdb backend. pdb_pgsql is a PostgreSQL passdb backend. pdb_multi is a backend which loads multiple passdb backends. These are provided because support for MySQL and PostGreSQL passdb backends has been removed from the Samba source tree, due to lack of an active maintainer.
tpe-lkm is a Linux kernel module implementing Trusted Path Execution, a security feature that denies users from executing programs that are not owned by root, or are writable. This closes the door on a whole category of exploits where a malicious user tries to execute his or her own code to hack the system. Since the module doesn't use any kind of ACLs, it works out of the box with no configuration. It isn't complicated to test or deploy to current production systems. The module also has a few other grsecurity-inspired features implemented as "extras".
Perl modules are notated in many different formats: "Foo/Bar/Baz.pm", "Foo::Bar", "Foo-Bar", etc. Module-Format allows one to take a list of modules in any format (including mixed ones) and output it in a consistent format that can be input to an installation program or an information querier.