Documentation of CAS Compliance really only consists of one document - the CAS Notice sent within 30 days of award of a covered subcontract. To determine the necessity of a CAS Notice you have two supporting documents to review and complete:
In a nutshell, CAS provides the government with a way to make some sort of sense out of the creative arithmetic government contractors use when they price FAR Part 15 proposals. FAR Part 15 pricing doesn't exist as a constant in real life. It's at best a flexible kind of conceptual mathematics. FAR 15 pricing comes into being when government contractors apply theoretical variables to floating numerical data, calculate fee based on a percentage of those imaginary costs, and forward to the government for award.
If you take into account the reasons for CAS applicability, the exceptions make sense. I say this because many industry professionals (including compliance experts) often argue that the FAR "is illogical" or impracticable - that the rules seem arbitrary in both development and application.