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Not just ~C, but ~A

This note is intended to amplify the remarks made by greek@hudson the other
day about ~C.

In VAXLISP, (FORMAT NIL "~C" #\Space) => "Space".
In Zetalisp, (FORMAT NIL "~C" #\Space) => " ".
Since the manual allows implementations to do what they want, neither of
these can easily be claimed to be a simple bug.

Worse, however, is that none of the description of ~A, PRINC, or 
*PRINT-ESCAPE* give me the sense of confidence that (FORMAT NIL "~A" #\Space) 
will come out with " " rather than "Space" or "#Space" since they all 
talk about doing like PRIN1 but without escape characters.

Since neither ~C nor ~A seems to specify for sure that it will output #\Space
as a space, the bottom line seems to be that CL does not specify a format op
(other than ~Q) which can reliably do the job! This is a sad situation indeed. 
I hope we can promptly clarify the behaviors of ~A and ~C in this regard.

At the same time, it would be good if any clarifications discussed what should
happen for characters which are not STRING-CHAR-P. I'd be content to see a
variety of things happen in this situation, but I'd like us to take some 
firmer stand if we could agree to. However, if we couldn't come to an agreement
on that, it certainly shouldn't keep us from fixing the problem for the common
case of things that are STRING-CHAR-P.