Description and status update on GELLO: A proposed standardized object-oriented expression language for clinical decision support

Margarita Sordo, Aziz A. Boxwala, Omolola Ogunyemi, Robert Greenes

Research output: Chapter in Book/Report/Conference proceedingChapter

31 Scopus citations


A major obstacle to sharing computable clinical knowledge is the lack of a common language for specifying expressions and criteria. Such a language could be used to specify decision criteria, formulae, and constraints on data and action. Although the Arden Syntax addresses this problem for clinical rules, its generalization to HL7's object-oriented data model is limited. The GELLO Expression language is an object-oriented language used for expressing logical conditions and computations in the GLIF3 (GuideLine Interchange Format, v. 3) guideline modeling language. It has been further developed under the auspices of the HL7 Clinical Decision Support Technical Committee, as a proposed HL7 standard., GELLO is based on the Object Constraint Language (OCL), because it is vendor-independent, object-oriented, and side-effect-free. GELLO expects an object-oriented data model. Although choice of model is arbitrary, standardization is facilitated by ensuring that the data model is compatible with the HL7 Reference Information Model (RIM).

Original languageEnglish (US)
Title of host publicationStudies in Health Technology and Informatics
Number of pages5
StatePublished - 2004
Externally publishedYes



  • clinical decision support
  • Expression language

ASJC Scopus subject areas

  • Biomedical Engineering
  • Health Informatics
  • Health Information Management

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