Technical atmosphere

A technical atmosphere (symbol: at) is a non-SI unit of pressure equal to one kilogram-force per square centimeter.

The symbol "at" clashes with that of the katal (symbol: "kat"), the SI unit of catalytic activity; a kilotechnical atmosphere would have the symbol "kat", indistinguishable from the symbol for the katal. It also clashes with that of the non-SI unit, the attotonne, but that unit would be more likely be rendered as the equivalent SI unit, the picogram.