lamford, on 2017-June-03, 14:58, said:
In the EBU, the following are considered natural for the purposes of alerting and regulation of partnership understandings:
( c ) A pass which does not unexpectedly convey values or specify suit holdings.
It does not say how many values have to be conveyed, or whether those values have to be guaranteed systemically.
What does it mean for a call to "convey" something other than it's part of your systemic agreements? But I agree that the case where it shows two possibilities, only one of which includes values, does not "convey values".
Outside of HUM, this doesn't usually come up with opening passes. But it's not uncommon for a player to have more values than they've previously shown, but no good bid available. This usually comes up in competitive auctions -- you'd normally show your extra strength with a NT jump, but you don't want to do that without a stopper in the opponent's suit, so you end up passing.