Is it legal to use memset(…, 0, …) on an array of doubles?

Question

Is it legal to zero the memory of an array of doubles (using memset(…, 0, …)) or struct containing doubles?

The question implies two different things:

Answer 1

Well, I think the zeroing is "legal" (after all, it's zeroing a regular buffer), but I have no idea if the standard lets you assume anything about the resulting logical value. My guess would be that the C standard leaves it as undefined.