This paper gives a summary of the work done by CEN TC 251 PT 004. The project team objective has been to investigate syntaxes of existing interchange formats (IFs) to be used in healthcare. A set of evaluation criteria have been developed based on functional requirements from two healthcare domains. 5 IFs; ASN.1, ASTM E1238, EDIFACT, Euclides and ODA have been evaluated. ASN.1 scores highest in the evaluation. However mapping from General Message Models (GMDs) to IF dependent message models (IFMDs) shows that all the IFs can be used. The project team recommends a strategy for development of GMDs, IFs and IFMDs.