From chemistry-request -8 at 8- server.ccl.net Fri May 18 14:00:06 2001
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Date: Fri, 18 May 2001 14:06:00 -0400
To: Doug Smith <dsmith:~at~:row2technologies.com>
From: Jonathan Brecher <jsb.,at,.camsoft.com>
Subject: Re: CCL:CAS Registry Numbers
Cc: "'chemistry-: at :-ccl.net'" <chemistry-: at :-ccl.net>

At 10:15 AM -0400 5/18/01, Doug Smith wrote:
>Can someone explain the structure of a CAS registry number and how it is
>generated?  According to the CAS web site, 336607-92-2 is the most recent
>CAS Registry Number as of this morning.  I know there is no chemical meaning
>or significance to the numbers, but what is each of the three fields and how
>are the numbers assigned?
>Doug

See http://www.cas.org/EO/regsys.html

Briefly:

o  The last digit is a checksum.
o  Everything up to the last digit represents a sequential number.  The
number above corresponds to the 33,660,792th item entered into their
database. (Approximately!  The numbers didn't quite start at 1, and just
because it was the 33.6 millionth item entered, that doesn't mean that all
of the other items are still present in the database.  Numbers are retired,
etc...)
o  The dashes are there just to make things look pretty.

Jonathan Brecher
CambridgeSoft Corporation
jsb _-at-_)camsoft.com