Rationale

Revise section of standard dealing with velocity measurement ("Proceedure A") to include Proceedure A.1 and Proceedure A.2, one measuring velocity via surface to surface and the other via a known-thickness location. make other revisions as needed to update the velocity measurement language to reflect that velocity at each test point is actually detrimental to overall thickness accuracy, since an average velocity over a single placement/mix design has been found to be more representative (and much faster) than individual velocity measurements