File with a .GPD extension contains a text description of a printer – information on attributes, options, supported commands and functions, and also descriptions of fonts or conditional instructions stored in GPD language. A note of this language is comprised of entries composed of an asterisk and the following attributes – a key word, its value, appearing after a colon, and the entries contained between curly braces.

GPD files are used within Microsoft Windows. They enable communication with a printer via Unidrv – the universal printer driver. GPD files are parsed by a Unidrv application – Universal Printer Driver.