My data vendor replied to me as follows:
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Firstly, it is nice to virtually meet you, I look after the Market Data Product.
Secondly, I’ve read the below email chain regarding your requirements. Reading between the lines it appears you are looking for the Tag50 to understand who is submitting the orders into the book, is my understanding correct?
Tag 50 is used by participants when sending orders to CME, so CME can identify who sent the order. The participant also needs to submit this ID when changing or deleting an order.
The exchange does not send this ID back in the market data feed, as to a way to identify the orders in the book. If this is what you are trying to do it would not be possible to identify the participants against each order. As a vendor we are limited to supplying what the exchange provides us, this is the same as any vendor and no one will be able to add to the exchanges feed to provide this information, if the exchange does not. Apologies for any confusion.
If you are trying to do something, please can you explain so we can help you further. Some more information on Tag50 can be found on the below link.
https://www.cmegroup.com/tools-information/webhelp/cme-customer-center/Content/tag50.html#Accessin