There is a lot of discussion on how to select seats on code share flights. The issue particularly is when an operating carrier's system is Amadeus.

There are 2 scenarios:
1) seat map for marketing carrier is available => no issues in this case.
2) seat map for marketing carrier is not available

I know from experience when generic seat requests do work (I presume in 1A it is ST/RQST/XX where XX is seat number or ST/NSSA or ST/NSSW but i cannot confirm yet).

And of course most agents do not know how to do it.

The question I have is a bit technical though - in Sabre the operating carrier PNR is always 'public', can be accessed by a traveller once the record locator is known.

However, in Amadeus the operating record seems to be hidden. Can someone enlighten me please in which form it exists and how to access it?

The reason i think Amadeus operating record is somehow accessible is that in my CZ eticket record (on CZ website) for an AF operated flight it is showing the flight with AF flight number and booking code Z (while the marketing flight is CZ with booking code I).