Al,

Thanks for the remarks. Apparently, one "Petrovsky" has slipped my
attention among al the other "Petrofsky"s. It will be corrected.

And again, you are right with the macro "loop". It  is time to
rewrite the thing, then. I will introduce a local macro to do the
work, that seems most transparent.

Sebastian.

P.S. I had been trying to do exactly the local macro binding thing
for some time before it dawned to me that it is not going to work with
the macros mechanism as specified in R5RS.