First, in my defense, it looks like Joost had some confusion about what you meant as well.

Second, A intersects B at 22, while B intersects C at ( 22 .. 33 ), and wholly contains D. The statement

B contains the set of B->{C, D}, C->{D}, A->{} etc.

seems to differentiate '->' from 'contains', as well as using two different ways of defining a set ( '{}', and 'the set').

In any event, I'm glad you got the help you needed.