[blml] convention

[Steve Willner]

> From: "Wayne Burrows" <wjburrows at gmail.com> 
> It only has to be one of the possibilities to be not conventional -
> willingness to play OR high-card strength OR length.

Under a literal reading of the definition, that isn't quite right. 
Showing any or none of the three meanings or overall strength is 
irrelevant to the classification, but if a call shows anything else 
_besides_ those things, then it's a convention.  There's also a WBFLC 
minute saying, in effect, that negative inferences don't make a call a 
convention.

The fact that people are disagreeing about a particular call shows that 
the definition isn't easy to understand.