problematic document for isascii(3)

[ntysdd <ntysdd at gmail dot com>]

Hi,
I found something buggy in the document.
The doc says "`isascii' is ANSI C", but it isn't.
It is a BSD extension.

Also the doc for isdigit says
"It is defined only when `isascii'(C) is true or C is EOF."

But isdigit is ANSI C so it should not rely on isascii.
And after reading the ansi draft, I think isdigit is defined
for anything representable as an unsigned char (plus EOF).

By the way, the doc says isdigit is a macro using a table.
I don't think it need be implemented in this way because
something like '0' <= C && C<='9' is good enough.