Semantics

Full Title or Meme

When an Entity can determine the "significance" of words in sentences.

Context

• Based on the obsolete idea that all of language can be divided into Syntax (order) and Semantics (meaning).
• Some data elements have meaning that is independent of the places where they are used. These cases are handled well with a Data Dictionary.
• For data elements that are context-dependent, the meaning cannot be known without reference to the context. These cases need a richer model.

Semantic Models

• Semantics in data processing goes back to the 1980's when EDI and XML structures were being defined.
  • In the case of EDI all semantics were context-dependent. The concept was introduced by Tom Jones at a meeting at MIT where a data type was defined to say that the following data values had meaning only in that document at that location.
  • In the case of XML, the contexts were established at the top of the document and the specific context tag was prepended to the element name. So if the context name was "x", an element of that context would appear as x:tag.
• Data dictionaries appeared in the databases with the EAR or Entity Attribute Relational models used with languages like SQL.
• The Semantic Web can be dated to a paper by Tim Berners-Lee's paper in 2001 and the publication of the OWL language in 2004.