DC (Dublin Core)
Dublin Core is a metadata format for describing documents and other objects. It is based on principles from the library environment. Its simplest version, the Dublin Core Metadata Element Set, consists of fifteen data fields. All of the fields are optional and can be repeated. As needed, the fields can be further specified by the use of qualifiers. Dublin Core can be represented in, for example, XML/RDF. Dublin Core is often used as a "least common denominator" metadata format for the exchange of metadata.
LMER (Long-Term Archiving Meta-Data for Electronic Resources)
For a fully functional strategy for the long-term archiving of electronic documents, it is essential to compile the appropriate technical metadata. There having been, at the time, no suitable standard for a metadata schema specifically for long-term archiving, the German National Library introduced its own schema, LMER, based on a model at the National Library of New Zealand.
METS (Metadata Encoding & Transmission Standard)
The METS schema is a standard for encoding descriptive, administrative, and structural metadata for objects in a digital library.
OAIS (Open Archival Information System)
The reference model adopted under the designation ISO 14271 describes an archive as an organization in which humans and systems work together towards the goal of preserving information and making it available to a defined body of users. OAIS conformity includes the assumption of responsibility for compliance with the framework specified in the reference model. However, this reference model specifies neither the design nor the implementation of an conforming OAIS archive.
URN (Uniform Resource Name)
A Uniform Resource Name (URN) is a Uniform Resource Identifier with the schema "urn" which serves as a persistent, location-independent identifier for a resource. The purpose of URNs is to uniquely identify a particular resource during its lifetime. A given resource can have a number of URNs assigned to it. Because a URN (as opposed to a URL) is independent of location or other characteristics of the resource, it can be retained even when the physical location of the resource changes.