qb45qck.hlp (Table of Contents; Topic list)
CLS Statement QuickSCREEN
  QuickSCREEN      Details      Example      Contents      Index
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CLS - a  device I/O statement that clears the display screen
 
Syntax
  CLS [{0|1|2}]
    ■ If all arguments are omitted, either the graphics viewport or the text
      viewport are cleared, depending upon previous uses of VIEW statement.
    ■ 0 clears the screen of all text and graphics.
    ■ 1 clears only the graphics viewport, if it is active.
    ■ 2 clears only the text viewport, leaving bottom screen line unchanged.
 
See Also  VIEW - to see how to activate the graphics viewport
          VIEW PRINT - to see how to set the text viewport
          WINDOW - to see how to customize the graphics viewport