.::. Some Random Terms .::. • Impact resistance Ability of ceramic tile to resist breakage - either throughout the body or as surface chipping - as the result of a heavy blow. In general, ceramic tile is not a resilient material, and care should be taken to avoid dropping heavy or sharp objects on its surface. Glazed tiles are more susceptible to surface chipping than unglazed tiles. International Standards are established for the impact resistance of ceramic tiles by measuring their coefficient of restitution (ISO 105455). .... • Relieving arch Arch built up in a wall to relieve thrust on another opening. .... • Lift rail The part of the sash, the operator uses to raise or lower the window. ....