Val procedure

  DECLARATION:  Val(S : String; Var Num; Var Error : Integer);

      PURPOSE:  Converts a string value to its numeric representation

         UNIT:  System

      REMARKS:  S is a string-type value, Num is an Integer-, or Real-
                Type expression, and Error is an Integer-Type variable.
                S must be in the set of character that makes signed whole
                numbers.  The converted value of the string, S, is stored
                in the variable, Num.  If the conversion was successful,
                Error is set to 0, otherwise it is set to the index of the
                offending character.