Vampyr, on 2016-May-18, 17:55, said:
Well, you can use exclusion.
And you can also safely use it once partner has denied a control in the suit, usually via cue bidding. Or, rarely, when you have a big hand and already know that you want to go to a grand slam but need to find out if partner has the ace of your void to decide between 7NT and 7 of the suit. And sometimes space is so limited that it is the best you can do even though it is flawed. As a general rule, those that take "never" rules to heart are weak players - there are nearly always exceptions.