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CAS Is Now Assigning 10-digit CAS Registry Numbers

To accommodate the continuing growth of substance information in the CAS REGISTRY^SM, CAS is now assigning 10-digit CAS Registry Number (CAS RN) identifiers for newly registered substances.  As announced earlier in 2007, CAS encouraged customers and business partners to take steps to be prepared for the adjusted format.

As CAS has done in the past, we are allowing for the growing collection of substances by adding another digit to the Registry Number. The 10th digit appears in the left-most position in the CAS RN. For example, a new CAS RN is seen in the following form:

xxxxxxx-xx-x

CAS customers who use the check-digit algorithm to validate CAS RNs or have a controlled-length CAS RN field in an in-house system were instructed to modify their systems to accommodate the additional digit.

For any questions, visit CAS REGISTRY, send e-mail to help@cas.org, or call CAS at 800-753-4227 (North America) or 614-447-3700 (worldwide).