If you ask about interline fares [fares which allow to have segments by other airlines without the code of a main airlines (ie AF segments in DL fare)] then the information is stored in a so called "RBD Chart 2" which is part of the fare. It is currently available only in GDSs. It is fare and route specific but exceptions in fact are rare and usually apply to IATA fares rather than to other interline fares.

If you ask about codesharing (less likely) then it is only the airlines being parts of the agreement which have the information. For a passenger such information can only be useful for 'free-sell' codeshare agreements when you want to guess whether or not specific class opened by operating carrier will trigger the opening of a certain class by a marketing carrier.