About T1-10: This Processing Standard contains important information and requirements about conditioning of material for treatment, treatment processes, and quality control applicable to all commodities treated under the AWPA Use Category System. This Standard uses SI (i.e., metric) units. English units are soft conversions and are for information only. About U1-10 The purpose of the Use Category System (UCS) is to provide a simple way of using the Standards of the American Wood-Preservers' Association (AWPA). The system was introduced in 1999, and defines a series of different exposures for treated wood products. Each exposure has a different degree of biodegradation hazard and/or product service life expectation. The system helps specifiers and product users to locate the appropriate AWPA Standards that provide recommendations for a specific combination of product and use environment.