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ULEX, or Universal Lexical Exchange, is an abstract message framework that provides an extensible data packaging format for the purposes of information sharing. This messaging framework is based on a plug-in architecture allowing program-specific implementations of the consistent and conceptually-compatible messages.

The framework provides concrete and abstract definitions of the important message artifacts, their structure and hierarchy.

ULEX message framework:
  • Defines top level objects such as Message, Data Item, Digest, Structured Payload and Attachment
  • Provides conceptual rules that tie ULEX structures into a coherent message
  • Uses W3C XML Schema constructs such as Abstract typing and group substitution to provide extension points for program-specific implementations.
To date there are two instantiations of this framework into specific data models: NIEM and UCore. The NIEM implementation is known as LEXS 4.0, and the UCore implementation is known as UCore 2.0 messaging framework.

Information about some important programs can be found in these helpful links:



  • ConTesA currently has support for ULEX 1.0 and the UCore 2.0 implementation.  Support for LEXS 4.0, which is based on ULEX 2.0, is also available.
  • The Schema Navigator Tool has direct support for ULEX 1.0.


Currently, the ULEX community shares in the LEXS community. You can find ULEX-specific forums or add a ULEX wiki page.