When trading on-MTF EDM/IDM values must be populated in the outbound quotes and any resultant ExecutionReport messages. For on-MTF requests here is a summary of the various Venue's behaviour:
Current UAT:
FYI for the future:
8=FIX.4.4|9=0302|35=b|49=BLP|56=MFMA_RFS|34=7|52=20191002-10:12:00|300=8|301=0|131=BLP.RFQ.800254719_MFTA|117=S1570011120.46998|297=5|58=Failed to convert to GPI, ShortCode=Dmitry_xxx DealCode=MFMA roletype=makerExecId DEAL_CODE: MFMA FIX_SESSION: MFMA_RFSQuoteReqId=BLP.RFQ.800254719_MFTA quoteId=S1570011120.46998 |10=202|
(Dmitry_002 was the correct EDM value in this case). We will convert this rejection into a QuoteResponse and forward the error message as-is.
Also, at the risk of me stating the obvious, these details are required on-MTF only - if OFF, or testing SEF then, again any values you provide will be ignored.
There can only be one EDM, one IDM. The two may be the same, but there cannot be multiple of each. The EDM and IDM values provided must be previously registered by the market participant and are used to unambiguously identify the one person considered to have primary responsibility for the transaction in each capacity.