What classifications and to what spec?

The AWS D17.1 aerospace welding specification has class A, B, and C welds.  They are assigned somewhat arbitrarily by the designer and or customer according to the anticipated service stress level and what they do is callout different inspection requirements and defect limits according to the assigned class.  Actually, D17.1 is intended to break it down by no risk if failure = C, loss of system if failure = B, and loss of aircraft if failure = A I think.