Usually a club will use another Assoc. Rules, like the APHA uses ASHA rules for their ranch horse division.
You can look and see maybe whose rules they are using, if in fact they are using another assoc. Rules.
I have found if they want to truly see a sliding stop the pattern will call for it.
I hope you go, I found the people to be great and it is very low key compared to a NRHA show. The ones I go to have a trail class, pleasure and cow working, it gives your horse plenty of things to do. You can enter them all or just one.