Abbreviation for Chemical Abstract Service. CAS numbers represent chemical substances recorded in the CAS Chemical Registry System.
This numbering system identifies chemical substances by an unambiguous computer language description of its molecular structure, including all stereo-chemical detail. The CAS number, which has no chemical significance, is simply a number assigned in sequential order to each substance as it enters the Registry System.
All specific substances reported in the world's scientific and technical literature and indexed in Chemical Abstracts (CA) since 1965 (when the Registry System began) are included in the master file.