grenv: I wouldn't say there is one set of universally accepted rules; indeed, there are many local variations. I have a friend from Persia, which might claim to be the birthplace of backgammon, who has educated me on the rules used in that country. However, there does appear to be only one set of rules used in international tournaments.

So far as I know there is no set of local rules that allows a player to use only one die if there is a move available for both, or to use only the smaller die when there is a move available for the larger; but it would not surprise me if such a set of rules existed. Nevertheless, I think Fencer's intention was to apply the rule set applicable to international tournaments.

It's clearly a matter of individual conscience whether to follow those rules, when the server allows moves that violate them. In the past, I've waffled on this point, sometimes taking the position that my following the international rules strictly gave an unfair advantage to unscrupulous opponents. Lately, I've chosen to do what makes me most comfortable, which is to follow the international rules and forgo opportunities to take advantage of what I see as a glitch rather than a "house rule".