There’s a detailed discussion of the code in a book we have, but I can’t find it right now. (A kid broke a bookcase, so we have books in piles ;-)
This page has a good description, very similar to what’s in the book. It might even be the same report:
Thanks,I will check that out-—a fascinating subject.
(I won’t even ask how a kid could break a bookcase.)
:-)
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