In DICOM, an Abstract Syntax is a set of rules that are negotiated for exchanging objects.
The Abstract Syntax identifies one SOP Class or a Meta SOP Class. The presentation context consists of the Abstract Syntax (what information is exchanged) and the Transfer Syntax (how it is encoded) used for that abstract syntax. The term abstract syntax is used in part because it is defined in one of the international standards that DICOM references. A DICOM conformance statement lists both presentation contexts that an application will propose during negotiation and those that it will accept.