Mine was actually a question as well. My thought was because of nano second accuracy, json won't be preferred. XML causes no issues here just the bloat.

https://www.fixtrading.org/standards/json-online/#issues-for... I guess so.

exactly, it is the same. basically the simplest way to parse is to split the message into key/value pairs separated by \x01 (SOH), and then inflate/enrich the message with field names and enumerations to make the message more understandable. the protocol is deceptively simple and the complexity moved to the validation instead, here's where the specification + versioning + vendor specific fields become complex because the devil is definitively in the details