PRSD_DISPLAY   Set or get global display verbosity level

 Print current display state
     PRSD_DISPLAY
 Retreve current display state
     LEVEL=PRSD_DISPLAY
 Set display state
     PRSD_DISPLAY ON
     PRSD_DISPLAY OFF
     PRSD_DISPLAY(LEVEL)

 DESCRIPTION
 PRSD_DISPLAY allows the user to control detailed output of PRSD Studio
 commands. By default, the PRSD Studio provides detailed display. Using
 PRSD_DISPLAY OFF, the user may switch off all display commands.
 Current display level may be also read into numerical variable LEVEL.