Linked data for libraries, museums and archives (LAM) draws on and integrates a broad variety of structured schemas and vocabularies, some of which have developed over a period of decades. In the linked data environment, all such semantic artifacts are expressed in RDF (Resource Description Framework) as data , and in the RDF context most of these types of data may also be called vocabularies . From the perspective of LAM practitioners, such semantic artifacts present themselves broadly as element schemas , which define the basic properties and classes according to which the data is structured, and value vocabularies , which provide pragmatically organized structures of concepts to which the resources they describe are related.