Hi.

> The real question is the semantics of BlockContextComposite.
> In some of the examples, the comma "means" AND, in some OR,
> in some a sort of NOT-AND, in some a sort of NOT-OR

Comma does not mean any of the above.

> We already _have_ messages that summarise "composites" in various
> ways, and they apply to collections. <snip>

Those messages don't allow comma.

Andres.