I was wondering if it is admissible for the "error" procedure
to be defined using the "raise" primitive of SRFI 21:

(define (error msg . args)
  (raise (make-error-exception msg args)))

where "make-error-exception" is implementation dependent.

I would like this to be explicitly permitted.  Note that because
exceptions can be intercepted with "with-exception-handler", it is
possible that a call to "error" will not display any error message.

So in fact my question is: what does it mean to "signal an error"?
I think it can't require printing an error message, because even
this is hard to specify (is the standard output used or standard
error?  what if there is no stdout and stderr?  can a window
with the error message pop up?  on what display?  can the printer
be used?  etc).

Marc