This paper analyzes the relationship between subject terms -- both authorized terms from controlled vocabularies and free-text keywords -- used to succinctly describe the content of the electronic theses and dissertations (ETDs) and the search terms entered by users to discover and access the ETDs. Identification of search terms and comparison of search results with subject terms used in describing ETDs provides a basis for assessing the relative usefulness of controlled-vocabulary subject terms supplied by professional indexers and free-text keywords supplied by authors of ETDs in facilitating access to ETDs. Arguably, there has been a shift in the way users search, access, and use information resources.

This paper presents results of an exploratory analysis of representation of dates in over 8 million metadata records from the Digital Public Library of America (DPLA), and compares it to Extended Date/Time Format (EDTF) specifications.