Back when the race class structure was different, leaving aside listed and group races along with wfa and set weight races, there were three classes of open handicaps they being (in class order): open, welter and highweight.

Highweights disappeared a few years ago (there always used to be a least one arun at Flemington on Cup Day) and they could best be described as being for low grade horses who had no where else to go - couldn't run in the restricted races and not good enough to run against the better open handicappers.

Welters were still run in Sydney, mainly at the midweek meetings until about three years ago, but they've now disappeared, but they still run them in Brisbane and Perth (they run races in Melbourne carrying that race class but they are not true welters, being more of races with restrictions such as Rs1WinLY or something similar).

Welters are races where the minimum weight in higher than an open handicap and are generally contested by older horses past their best or the younger ones on the up thru their classes. Very good races to bet on as usually there are only a very few genuine chances.

Some on this forum may well remember the old saying, always back the topweight in a welter, for the very simple reason they had a very good strike-rate in such races as class often prevailed.