Trunc function

  DECLARATION:  Trunc(X : Real);

      PURPOSE:  Truncates a real-type value to an integer-type value

         UNIT:  System

  RESULT TYPE:  LongInt

      REMARKS:  Trunc accepts X as a Real-Type expression, truncates
                it (rounds it down toward 0, and returns the result as a
                LongInt.

 RESTRICTIONS:  A Run-Time Error occurs if the returned value is not
                in the range of LongInt