Represent values of logical expressions.
     
    Syntax
      
      
          
          
            
              
                { [ YES | TRUE ] | [ NO | FALSE ] }
               | 
            
          
        
 
      
        
          - YES | TRUE
 
          - A value that signifies a valid result for a logical expression.
 
        
        
          - NO | FALSE
 
          - A value that signifies an invalid result for a logical expression.
 
        
      
     
    Note
      
      You must
use these values in a procedure even if alternate values are given in
the FORMAT specification for a field or variable.