QCA-2, Visual Quality Characteristics of Aluminum Extrusions (First Edition, December 1993), sets the preferred terms and definitions of cause for the visual quality attributes of aluminum extrusions, with illustrations of typical conditions. It provides a common vocabulary for what is seen on an extruded surface — die lines, streaks, pick-up, scratches, dents, blisters, color variation and similar characteristics — and explains how each condition arises, so that customer and extruder can discuss appearance requirements precisely. The document supports the preparation of visual acceptance standards and is used in quality agreements, first-article inspection and the resolution of appearance-related claims.