Metadata aggregators facilitate the connection of disparate sources of data and/or provide the means for others to connect to the data stored in their repositories through common content identifiers. There is no single standard for metadata content identifiers which makes mapping alternate identifiers across ecosystems commonplace, but no less cumbersome. Commercial metadata aggregators typically leverage a proprietary content identifier specific to their ecosystem, such as TMS ID for Gracenote or Cosmo ID for Tivo.