Yesterday's blogicle noted that metadata will be increasingly important component of DRM 3.0. The Wiki article on the subject points out that metadata has a broad range of meanings, uses, and contexts that share in common the idea of "data about data." Regarding rights management and related areas, metadata describes various objects, including, but by no means limited to, books, serial publications, music, and audiovisual works.
A wide variety of international, open, and proprietary standards exist for various kinds of real and digital objects. Among the latter are the well known ISBNs for books and the ISSNs for serial publications. The familiar barcoded UPCs are administered by a global non-for-profit organization, GS1, that has affiliates in the US and numerous other countries.
Here are a few examples of metadata for digital goods. Digital Object Identifiers (DOIs) are a standard for digital objects generally, while ISANs are metadata for audiovisual objects, i.e., audio and video. Gracenote's MusicID is a major database of metadata relating to music tracks which is now being augmented by metadata for video.
From time to time I'll drill down on various metadata databases and their relevance for rights management in the broadest sense.