arrays

["Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>]

    "Vectors whose elements are restricted to type bit are called bit-vectors"

    This implies strongly that a bit vector won't let one store any other value
    than 0 or 1.

This one is right in my opinion.  Sloppy wording in some of the other
descriptions you quote.

    So, is this a bit vector?

    #(1 0 0 1) 

No.

    should things like BIT-NOT which specifically want a bit vector
    work on it.  Does it return a general vector like this in this case rather
    than something like *0110???

They have to work on bit vectors.  It is an error to give it anything
else.  If an implementation wants to handle general vectors that happen
to be full of 1's and 0's, that's a legal extension; in such cases, it
is no business of Common Lisp what it returns.

-- Scott