Imported from previous forum
FIX 4.4 provides the Parties component which should be used to identify all actors from a business point of view. This includes regulatory information. Tag 115 is for the session layer and strictly speaking not available on the application layer. Tag 217 cannot be used in isolation is part of a repeating group to fan out information such as IOIs, news or emails. It is not part of the order maintenance messages.
MPID may have been implemented in more than one way. For example, NYSE Euronext required tag 109 (ClientID) for FIX 4.2. This field has been deprecated and superseded with PartyRole = 3 (Client ID) as of FIX 4.3. Another option is to use PartyRole = 11 (Order Origination Trader) and/or 13 (Order Origination Firm). The latter is semantically clearer from my point of view. However, tag 1724 was introduced with Extension Pack 135 which also added OriginatingDeptID (1725) and ReceivingDeptID (1726) as explicit fields. Please see EP135 (http://www.fixtradingcommunity.org/pg/extensions/extension-pack?ExtensionID=EP135) for details.
In FIX 4.4 when using OrderOrigination set to 3, OrderReceivedfromAnotherBrokerDealer, FINRA OATS requires the MPID of the other broker dealer. What is the correct FIX tag to be used on New Order Single etc... for this value. Is is OnBehalfofCompID[115] or RoutingID[217] or ???.
Thanks Hanno. Feedback is much appreciated. We will go forward using one of the PartyRoles you highlighted, likely 13 (Order Origination Firm).