[jplur]

I've been thinking about how to format meta data for my creative files - JSON-LD with my personal @context spec is an interesting idea.

[mehh]

There is more than likely an ontology already defined for the creative meta data, if so you should look at using that rather than inventing your own.

[Fannon]

http://schema.org/ is probably the best choice to go with already established standards. I think there are (even today) some SEO benefits here and for the future maybe some more exciting things.