Syntax:        TXPSOURCE(<expN>)

     Purpose:       Designates the location to feed paper or prints
                    current page.

     Argument:      <expN> is command to locate the paper source or to
                    print the current page.

                    <expN> =  0 -  Print current page (paper source
                                   remains unchanged.
                              1 -  Feed paper from the upper paper
                                   tray
                              2 -  Manual paper feed
                              3 -  Manual envelope feed
                              4 -  Feed paper from lower paper tray
                              5 -  Feed from paper deck
                              6 -  Feed envelope from optional
                                   envelope feeder.

     Returns:        0  Successful
                     1  <expN> not numeric
                     2  Invalid value for <expN>

     Usage:         TXPSOURCE() is useful anytime you need to change
                    the source of your paper. Not all LaserJet
                    printers support all possible paper sources. Refer
                    to your user manual for printer configuration. It
                    is also used to print page if you did not use the
                    normal "@ col, row say" command to print your
                    page.

     Example:       * Print from lower tray containing special forms
                    _ret_code = TXPSOURCE(4)
                    (Print forms routine)

                    * Return paper source to top tray
                    _ret_code = TXPSOURCE(1)
                    (Print from top tray)

                    * Request manual paper feed
                    _ret_code = TXPSOURCE(2)
                    (Print manually input form)

     Printers:      Not all LaserJet printers support all possible
                    paper source options. Refer to your reference
                    manual for your printer configuration.