The following example uses SET PRINTER ON and OFF:

set printer to // Set printer to default
set printer on
? "Hello" // to printer
set printer off
? prow( ),pcol( ) // only displayed to screen
close printer // initiate printing

set printer to // resets to default
set printer to prn // sets to DOS output device
set printer to lpt1
set printer to null
set printer to file Test
// Test.prt receives streaming output, including any control codes,
// that would have gone to the printer.