When using %DEC, you are not allowed to specify %LEN(targetVar) and %DECPOS(targetVar) for the second and third parameters of the %DEC built-in function. The code below illustrates how to use named constants to circumvent this shortcoming.

     D numVar          S              7P 2                                 
     D charVar         S             10A   Inz(' 543.21')                  
                                                                           
     D NUMLEN          C                   Const(%len(numVar))             
     D NUMPOS          C                   Const(%decpos(numVar))          
                                                                           
     C                   EVAL      *INLR = *ON                             
      /free                                                                
                                                                           
          numVar = %dec( charVar : 7 : 2);     // Valid                    
                                                                           
          numVar = %dec( charVar : %Len(numVar) : %decPos(numVar)); // Fail
                                                                           
          numVar = %dec( charVar : NUMLEN : NUMPOS );  // Valid            
                                                                           
          return;                                                          
      /end-free 

As seen on line 14 above, the named constants NUMLEN and NUMPOS may be used when you want the target variable's attributes to influence the %DEC built-in function. Line 12 illustrates an assumed valid syntax, but does not compile. So the code on line 14 is necessary, or worse, the code on line 10 (hard coding the values) may be used.