CAS Registry Number, CAS Number, Chemical Abstracts Service Registry Number, Chemical Abstracts Service (CAS) Registry Number, Chemical Abstracts Service index number, CAS RN, CASRN
a unique identifier for a chemical substance, a unique numeric identifier with no chemical significance. It includes up to 9 digits which are separated into 3 groups by hyphens. The first part of the number, starting from the left, has up to 6 digits, the second part has 2 digits, and the final part consists of a single check digit.
