Four of the escape functions are used to retrieve information about the selected device and its settings. The GETPHYSPAGESIZE escape retrieves the physical page size of the output device (in device units), the smallest addressable units on the device. For example, one-fortieth of a millimeter is the smallest addressable unit on some vector devices. A pixel is the smallest addressable unit on a dot-matrix device. The GETPRINTINGOFFSET escape retrieves the distance (in device units) from the upper-left corner of the page to the point at which printing begins. The GETSCALINGFACTOR escape retrieves the scaling factors for the x- and y-axes of a device. The scaling factor expresses the number of logical units that are mapped to a device unit. The QUERYESCSUPPORT escape determines whether a particular escape function is implemented on a device driver. If the escape in question is implemented, QUERYESCSUPPORT returns a nonzero value. However, if the escape is not implemented, QUERY-ESCSUPPORT returns zero.