In terms of Metadata, let me offer some perspective from the world of metadata standards. Its a world that comes from both the Library and eLearning perspectives.
The starting point is Dublin Core, dubliccore.org.
It's a minimalist set of metadata from a Librarian's perspective.
Title, Author, Description, ID, Date, that's spirit of it.
This is quite generic and applies to anything.
Came about at a meeting in Dublin, OH, home of OCLC.
OCLC is the biggest provider of MARC records, which drives
library catalog systems. DC is much, much simpler than MARC
(and I've had to deal with MARC in my career).
Next up the line is LOM or Learning Object Metatdata.
IEEE is behind this, and the original work came from IMS.
LOM contains Dublic Core as a proper subset
and adds to it for eLearning specific purposes.
LOM is also a part of SCORM
Going sideways, there is METS or Metadata Encoding and Transmission Standard.
This is from the U.S. Library of Congress.
METS does have some fair following in digital preservation in the US Higher Ed
One more to note, that's MPEG-21. http://www.chiariglione.org/mpeg/standards/mpeg-21/mpeg-21.htm
. This is metadata that's directly within an MPEG.
Not widely used, part of the next generation of MPEG specification.
As you might notice, there's some chaos in this realm. IEEE has launched
a working group that is trying to resolve LOM, METS and MPEG-21.
It's chaired by Kerry Blinco
Technical Standards Adviser
Department of Education Science and Technology (DEST). Australia.
And Kerry is as good as anyone to lead this herd of cats.
For Edukalibre, I think DC is a reasonable 1st step, with LOM as the next one.
There are XML
schemas that can be used for the syntax. Exact meanings, well
that will depend on the communities of practice, otherwise known as "Profiling".
We are building authoring tools that could use LOM for it's metadata, and we'd be happy with just DC.