Thanks to all who have responded in this thread. I will follow up offline.
Re the question of terminology, and minority languages in particular, here
are a few quick thoughts (with apologies for taking this off on a tangent):
1. I hadn't thought of minority being offensive, but I guess we need
though we wouldn't think to call it, or Spanish or English, etc. As Francis
puts it, situational minority languages. But that just shows how dependent
the term is on context.
To avoid taking credit for this, I took the term from Peter Trudgill's
paper, Ausbau sociolinguistics and the