Please advise on the fields FIX recommends to represent the post trade transparency field - obligation bearer.
Obligation bearer has the obligation to report the trade for post trade transparency. Either one of the parties will be an obligation bearer.
You have two options, depending on what else you need to convey about that party. Both options involve the use of the Parties component with PartyID(448)=<bearer> and PartyIDSource(447)=N (LEI) (source depends on the jurisdiction but LEI is a good choice).
Option 1: PartyRole(452)=116 (Reporting entity) if you only want to flag the party as obligation bearer
Option 2: PartyRole(452)=1 (Executing Firm) (or whatever you need to flag the party as) in combination with the party subgroup with PartySubID(523)=Y and PartySubIDType(803)=49 (Reporting entity indicator)
Thanks Klein for the reply.
Using Parties components seems to be the right thing to do here.
Regarding using PartyRole(452)=116 (Reporting entity) or PartySubIDType(803)=49 (Reporting entity indicator) in either options, the obligation bearer even though have the responsibility for reporting, can ask the other party to report on their behalf. So in all the cases, obligation bearer may not be the party who is actually submitting the report.
Also, there is one more dimension for this query. We may need to report it for ESMA as well as FCA.
You can use PartyRole(452)=72 (Reporting intermediary) for the one actually submitting the report.
You can use OrderAttributeType(2594)=10/11 to express whether the order is subject to EU/UK share trading obligations (or both if you send both values). See EP250 (https://www.fixtrading.org/packages/fix-share-trading-obligation-extension-ep250/) for further details.
Thanks for your replies Klein, much appreciated