[pro] couple questions about dynamic bindings

There are some tests in the common-lisp test suite with dynamic binding that I don't understand. If someone could help shed some light on them I'd appreciate it.

progv makes it's arguments special. I don't understand how they can be a different special than the one declared in the let. I'd love an explanation.

(let ((x 0)) (declare (special x)) (progv '(x) () (boundp 'x))) ==> NIL

(let ((x 0)) (declare (special x)) (progv '(x) () (setq x 1)) x) ==> 0

Thanks,

Greg