Glue bond classification is a function of veneer grade and adhesive performance.  The bond classification is related to the moisture resistance of the adhesive bond under intended end-use conditions and does not relate to the physical (erosion, ultraviolet, etc.) or biological (mold, fungal decay, insect, etc.) resistance of the panel. Plywood panels with an Exterior glue bond rating are suitable for repeated wetting and drying or long-term exposure to weather, moisture, or other conditions of similar severity.  Plywood panels with an Exposure 1 rating are suitable for uses not permanently exposed to weather and are intended to resist the effects of moisture on structural performance as may occur due to construction delays or other conditions of similar severity.