Originally Posted by
mherdeg
And indeed I've quoted the EF tool in my original post which shows that this particular AC fare basis would book into UA M when booked as a UA flight number. But I don't see an ExpertFlyer tool that tells you how to interpret the booking class from a codeshare to the prime carrier once you've issued the ticket.
If I understand your question, the Booking Class search is part of the Fare Information results page. A third icon next to every fare result along side the Fare Rules and Routing Rules buttons. It's mentioned on the lower half of page 10 of the User Guide:
http://www.expertflyer.com/user-guide.pdf