I was looking for some numbers for the Pegasus and came across a BGA document that listed max gross weights for many gliders. The chart had two different max gross weights, one from the manual and one titled "BGA Concession - non-aero-batic" which was, IIRC, 3% higher. I've never heard of this term before. I know that max gross weights have some safety margin built in but what is this 3% and how did BGA arrive at it?