Watanabe, T. and Seta, K. (Eds.) (2015). Proceedings of the 11 th International Conference on Knowledge Management. Representation of Recorded Knowledge and Extended Date/Time Format: A Case Study of the Digital Public Library of America Oksana L. ZAVALINA a* , Mark E. PHILLIPS a , Priya KIZHAKKETHIL a , Daniel Gelaw ALEMNEH a & Hannah S. TARVER a a University of North Texas, United States of America *oksana.zavalina@unt.edu Abstract: Standardized representation of such properties of recorded knowledge products as important dates in their lifecycle facilitates discovery and transfer of knowledge. Among the multiple date and time format conventions, the Extended Date/Time Format (EDTF) specification is one of the most consistent and flexible, allowing for standardized representation of virtually all possible kinds of dates and date ranges. The expressivity of this specification makes it a candidate for becoming a single standard for encoding and normalization of dates and times in modern large-scale centralized databases which provide open access to vast amounts of cultural heritage data. This paper presents results of a study that analyzed representation of dates and time in one of the largest aggregators of digital content in the world -- the Digital Public Library of America (DPLA). The data strings of Date metadata field in over 8 million of DPLA metadata records were analyzed for compliance to EDTF specifications. The findings demonstrate both similarities and differences in date and time representation across DPLA content hub and service hub provider groups. This benchmark study provides empirical data – at both the individual provider level and the group level – about the overall rate of application of Date metadata in DPLA metadata records, distribution of EDTF-valid and non-EDTF-valid date strings by EDTF levels, and the most common date patterns across DPLA metadata. Keywords: Metadata aggregations, metadata values, dates, EDTF, standardization, data curation 1. Introduction 1.1. Digital Public Library of America In the past decade, there has been an unprecedented growth in the amount of information generated and managed by cultural heritage institutions. National libraries, academic and public libraries, archives, museums, and other public-spirited organizations throughout the world, have built digital collections and provided access but these collections often remain in separate pockets or silos. Large-scale aggregations such as Hathi Trust, Internet Archive, and the like, now bring together millions of information objects – either produced by digitization projects or born-digital – from hundreds of individual digital collections. The Digital Public Library of America (DPLA) is currently one of the most prominent such aggregations. Arising out of a vision of a United States national digital library, shared by librarians, scholars, and educators, DPLA brings “different viewpoints, experience, and collections together in a single platform and portal, providing open and coherent access to our society’s digitized cultural heritage” (“About”, dp.la, 2015). DPLA was launched in April 2013 with support from a number of funding agencies (Mitchell, 2013). Functioning on a distributed network model, DPLA consists of a group of national partners which are categorized as content hubs and service hubs (Ma, 2014). Content hubs constitute large libraries, museums, archives and other digital repositories which maintain a one-to-one relationship with DPLA. They provide hundreds of thousands of unique metadata records which represent digital objects such as online texts, photographs, manuscripts, artwork, etc. from their collections and also maintain and enhance these records as needed. Some of the content hubs are ARTstor, California Digital University, The U.S. Government Printing Office, and Harvard Library. Service hubs are state, regional, or other collaborations which host, aggregate, or otherwise bring together digital objects from cultural heritage institutions. The unique metadata records of the service hubs are provided to the DPLA through a single data feed such as OAI-PMH. Some of the service hubs of DPLA are the Connecticut Digital Archive, Digital Library of Georgia, and The Portal to Texas History (“hubs”, dp.la, 2015).