A quad is an extension of a triple to include a fourth section—thus the change from triple, three-part, to quad, four-part—that provides context for the triple, such as the Uniform Resource Identifier (URI) of the graph as a whole. While an triple takes the form of
<subject><predicate><object>, a quad extends that to be
<subject><predicate><object><context>. In the case of a named graph, this
<context> piece is the
<graphname>. Although casual speech about Linked Open Data (LOD) tends to refer most often to triples and triplestores, many Linked Data (LD) repositories are now quad stores and quads are commonly used, including by LINCS.
- W3C (2014) RDF 1.1 N-Quads: The following example shows a subject (spiderman), predicate (relationship/enemyOf), and object (green-goblin), and provides context to the triple by referring to a graph about the Spiderman domain (graphs/spiderman).
- W3C (2014) RDF 1.1 N-Quads