The ETsz() instruction requires the user to input lattitude, longitude, elevation, and crop type for a station's location in order to generate accurate calculations of ET. The Generic_ET_107_ETsz.CR1 and Generic_ET_107_ETsz_Windsonic.CR1 programs use the ConstTable() intruction to create a constants table that allows the user to easily input these values using Loggernet, PC400, or a keyboard display. These values only need to be set once, during station set up.