CAS Registry Number: Chemical Abstracts Service Registry Number is a unique identifier for a chemical and its synonyms. CAS numbers identify the chemical, but not its concentration or specific mixture. CAS Registry Numbers are assigned by the Chemical Abstracts Service, a division of the American Chemical Society.
A package is a small container in which a quantity of something is sold. Packages are either small boxes made of thin cardboard, or bags or envelopes made of paper or plastic. ...a package of doughnuts. It is listed among the ingredients on the package.
Furthermore, the term package has other uses in software. A component is a similar concept, but typically refers to a higher level; a component is a piece of a whole system, while a module is a piece of an individual program.