We are the buy-side. We communicate allocations at the time we place the order (v4.4), and the sell-side communicates the allocations to the custodian. When an order is partially executed, the sell-side communicates the partial allocations to the custodian via a file. Could the sell-side use the Allocation Report message to communicate the same partial allocations to us? Thank you.
Yes, the elaboration for the message in FIXimate (http://fiximate.fixtrading.org/latestEP) says “Sent from sell-side to buy-side, sell-side to 3rd-party or 3rd-party to buy-side, the Allocation Report (Claim) provides account breakdown of an order or set of orders plus any additional follow-up front-office information developed post-trade during the trade allocation, matching and calculation phase.”
ExecAllocGrp can be used to allocate (partial) executions of orders.