The listing of possible defects of a unit, classified according to their seriousness.

Commonly used classifications:

• Class A, B, C, D
• Critical, Major, Minor, Incidental
• Critical, Major, Minor

Definitions of these classifications require careful preparation and tailoring to the product(s) being sampled to enable accurate assignment of a defect to the proper classification. 

Tip excerpted from: The Professional's Guide to Maintenance and Reliability Terminology by Ramesh Gulati, Jerry Kahn and Robert Baldwin