The open access movement has highlighted the barriers that exist for users to gain access to significant portions of the research literature. The open data approach seeks to extend the principles of open access to the data and code that supports the published scholarly record. Current metadata is inadequate to allow information researchers to evaluate claims made about data archiving practices. Assessing current archiving practice and understanding the impact of archiving policies requires improved metadata. We propose that information researchers create an infrastructure for the collection of metadata about data use in the research literature, and that infrastructure should itself be open. The availability of metadata on data use would enable the calculation of archiving indices, just as citation data enables the calculation of the h-index.