Glass heat-treated in a special process so that it has a better resistance to bending, impact, or thermal shock than ordinary glass of the same thickness; when broken it falls into small, regular fragments instead of large, random-sized shards
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}