Client use a third-party service between the bridge (PrimeXM) and LSEG. This service essentially handles messages between the bridge and Refinitiv LP and converts them to a common language called ‘FIX-based’.
For example, taking 'market data request' type messages from Refinitiv - "give me a ticking feed for Bid/Ask/etc for an equity-type instrument".
We were told however, that PrimeXM can take 'normal' market data (ie. ticking Bid/Ask/etc) from Refinitiv. The issue is that we do not know if they can convert the protocols you use (RFA/SFC/etc) to FIX.