perClass Documentation
version 5.1 (11-May-2017)
 SDDISPLAY   Set or get global display verbosity level

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

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

sddisplay is referenced in examples: