FIXML
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.
FIXML Documents
FIXML Schema - Latest EP 698.26 KB 1036 downloads July 24, 2017
FIXML Schema package for the latest published FIX 5.0 SP2 Extension Pack: EP258 ...
FIX 5.0 SP2 Volume 1 Specification with 20110818 Errata 1.20 MB 1133 downloads July 24, 2017
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...FIXML Reference