FIXML is the XML encoding used within FIX. FIXML is widely adopted for derivatives post trade clearing and settlement globally. FIXML is also used for reporting.
The FIXML encoding standard is currently included in Volume 1 of the FIX 5.0 Service Pack 2 specification – FIXML Syntax and FIXML Design Rules. A separate document of the FIXML encoding specification is currently under development.
FIX 5.0 SP2 Volume 1 Specification with 20110818 Errata 1.20 MB 524 downloads
Volume 1 of the FIX 5.0 Service Pack 2 (with 20110818 Errata) contains the FIX tag-value syntax rules and the FIXML Schema syntax rules in the "FIX Protocol Syntax" section - FIX Tag=Value Syntax and FIXML Syntax.Create date: July 24, 2017