The Predefined and Driver Defined buttons specify whether the data that describes the name of a single paper size is selected from the predefined names supplied by the Universal Printer Driver or by the minidriver. This information will be presented to the user. (Prior to Windows 3.1, applications had no way of obtaining the name of a paper size other than via its predefined ID value.)
For the Diconix 150 Plus, the Predefined control is set.
For the HP LaserJet IIP, the Predefined control is set.