The CDIF family of International Standards is primarily designed to be used as a description of a mechanism for transferring information between modelling tools. It facilitates a successful transfer when the authors of the importing and exporting tools have nothing in common except an agreement to conform to CDIF. The language that is defined for the transfer format also has applicability as a general language for import/export from repositories. The CDIF semantic metamodel defined for CASE also has applicability as the basis of standard definitions for use in repositories. The International Standards which form the complete family of CDIF standards are documented in ISO/IEC 15474-1:2002, Information technology — CDIF framework — Part 1: Overview. These standards cover the overall framework, the transfer format and the CDIF semantic metamodel. This International Standard defines the State/Event Subject Area of the CDIF semantic metamodel. This subject area contains meta-objects that describe the entities of state transition diagrams and state transition tables, and also meta-relationships and meta-attributes that are necessary for available state transition.