Tau Rēhita CAS

A CAS Registry Number is a unique identification number, assigned by the Chemical Abstracts Service (CAS) in the US to every chemical substance described in the open scientific literature, in order to index the substance in the CAS Registry. This registry includes all substances described since 1957, plus some substances from as far back as the early 1800s. It is a chemical database that includes organic and inorganic compounds, minerals, isotopes, alloys, mixtures, and nonstructurable materials. CAS RNs are generally serial numbers, so they do not contain any information about the structures themselves the way SMILES and InChI strings do.