[BLD] Review of editor's draft 18 May

Harold, Michael,

I have only one major comment re this version of BLD (and wrt last 
call), and that is with respect to the definition of an external 
FORMULA: it is defined as External(ATOMIC), and I do not really 
understand what an External(Equal), an External(Member), an 
External(Subclass) nor an External(Frame) are.

Any other remarks I could do are minor editorial comments.

One question, though: in BLD, a named-argument UNITERM cannot have 
repreated key, inBLD, right? I understood that that possibility was one 
of the main reasons to have them NAU, though?

Cheers,

Christian