This document defines an abstract syntax on which RDF is based, and which serves to link its concrete syntax to its formal semantics. This abstract syntax is quite distinct from XML's tree-based infoset [XML-INFOSET]. It also includes discussion of design goals, key concepts, datatyping, character normalization and handling of URI references.
The idea of markup languages was apparently first publicly presented by the engineer William W. Tunnicliffe (1922-1996) from Washington, D.C. In September of 1967, during a meeting at the Canadian Government Printing Office, Tunnicliffe gave a presentation on the separation of information content of documents from their format.