I see. If it is an actual "breed" class then most shows require you to provide registration papers from that breed association along with the animal at check in.
That takes the guess work out for you. Also, some shows we show at let you show 3/4 or more Simmentals in the Simmental breed show. The American Simmental Association registers calves 1/2 blood or more, so it is represented on that animals papers.
Most shows have an All Other Breed (AOB) shows for breeds with less than a set number of entrants as well as a Commercial Show. Those would be the classes that the Reg. papers are not required or not needed.
I hope this helps.r