The GreEscape handling routine in the presentation driver supports the DevEscape function and its escape codes at the API. While the primary function of GreEscape is to implement the required support for the defined escape codes, it can be used to implement additional escape codes. There is a set of defined ranges for additional escape codes. The range chosen determines how the operating system processes the escape code when it is received as a parameter to DevEscape. On entry to GreEscape, the value of lEscape on the stack identifies the escape code. The action taken is determined by the escape code and the physical device that the presentation driver supports.