The simple answer to that is NO. There are no industry-wide accepted standards for these definitions. Nor are there accepted definitions for wide, extra wide, standard, or anything else.
This renders these terms almost meaningless, and leads to many off the rack saddle returns. We use bar designations with associated standards for rafter angle, rocker, flare and other elements and we know what changes to length or gullet width have on the overall dynamic of fit. Every horse is different. Every horse’s biomechanics are different. Unfortunately, saddle fitting isn’t as easy as setting templates on a horse’s back and seeing which one looks best, but we are here to help you with years and years of practical experience.