Hello, I want to use the User Defined Fields available. We wanted to use UDFs internally within our firm and saw that these don’t need to be registered (tags 10000 and less than 20000) as documented on this page https://www.fixtrading.org/online-specification/introduction/#user-defined-fields. I wanted to check that for these 9999 tags - are we also able to create User Defined Components to group the UDFs under. Or can we assign to existing components or just the root message like ExecutionReport
Many Thanks for your help Regards Ian
@ianworsfold, you can enhance standard components as well as the root level of standard messages with UDFs. You do not need to define your own components. You should avoid creating your own repeating groups, also for internal purposes. The closer you stick to the FIX standard, the easier it is to convey internal information to the outside, should that be required at some point in the future.