In the late 1990s, following the development of Dublin Core™ qualifiers, the term Simple Dublin Core™ was coined to denote metadata about a single resource, using only the fifteen properties of the Dublin Core™ Metadata Element Set, with string values, and without qualifiers.
Simple Dublin Core™ was the product of a time when the Dublin Core™ Metadata Element Set was widely understood as the specification of a record format. At the time, it was also assumed that metadata should consist of textual values indexed for retrieval. This pattern was widely deployed after 2000 in systems supporting the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH), which required that an OAI-PMH repository expose records using an XML format,
oai_dc, which may be seen as a serialization of Simple Dublin Core™. Due to the popularity of such formats, many people still refer to the Dublin Core™ Metadata Element Set and Simple Dublin Core™ interchangeably.