The PRN - Printable File is created when a user selects the print option but chooses to send the document to a file instead of to the printer. The file contains printer configuration information. The information for the printer will include the number of pages to be printed and the printer tray to be used.
A PRN document can be printed on a Windows PC by using right click to open a menu box, then select "Microsoft Office Imaging" from the menu, the file may also be printed using the Windows command line. To print through the command line you will need to know the filename, the computer name, the shared printer name and if the printer uses a USB or a parallel port connection. If you know that information you need to go to the "Start" menu, open the "Run dialog", then enter cmd and enter. For USB printers, "Copy /b filename.prn \computer nameshared printer name" or for parallel printers, "Copy /b filename.prn \computer nameshared printer name LPT1", no quotes and replace the generic names with actual file/device names.
For printing on Mac OS X just drag and drop the file on the printer icon.