EP049 – Security XML Symbology

This proposal formalises a way to carry an XML product description, primarily an FpML payload, alongside conventional FIX security identification. FIX 4.4 had overloaded SecurityID, and FIX 5.0 used EncodedSecurityDesc. Implementations found both approaches inadequate because firms could need SecurityID and EncodedSecurityDesc for their normal purposes while also carrying an FpML product description.

The proposed solution adds SecurityXMLLen, SecurityXML and SecurityXMLSchema to the relevant instrument components. This separates the embedded XML payload from conventional identifiers and descriptions, supports schema identification, and allows multiple instrument contexts to use an integrated XML description while preserving transformation between tag-value FIX and FIXML.