/sys$common/syshlp/helplib.hlb Lexicals, F$CVSI, Examples  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    1.$ A[0,32] = %X2B
      $ SHOW SYMBOL A
        A = "+..."
      $ X = F$CVSI(0,4,A)
      $ SHOW SYMBOL X
        X = -5   Hex = FFFFFFFB  Octal = 37777777773

      This example uses an arithmetic overlay to assign the
      hexadecimal value 2B to all 32 bits of the symbol A. For more
      information on arithmetic overlays, see the description of the
      assignment statement (=).

      The symbol A has a string value after the overlay because it
      was previously undefined. (If a symbol is undefined, it has a
      string value as a result of an arithmetic overlay. If a symbol
      was previously defined, it retains the same data type after
      the overlay.) The hexadecimal value 2B corresponds to the ASCII
      value of the plus sign (+).

      Next, the F$CVSI function extracts the low-order 4 bits
      from the symbol A; the low-order 4 bits contain the binary
      representation of the hexadecimal value B. These bits are
      converted, as a signed value, to an integer. The converted
      value, -5, is assigned to the symbol X.

    2.$ SYM[0,32] = %X2A
      $ SHOW SYMBOL SYM
        SYM = "*..."
      $ Y = F$CVSI(0,33,SYM)
      %DCL-W-INVRANGE, field specification is out of bounds -
         check sign and size
      $ SHOW SYMBOL Y
      %DCL-W-UNDSYM, undefined symbol - check spelling

      In this example, the width argument specified with the F$CVSI
      function is too large. Therefore, DCL issues an error message
      and the symbol Y is not assigned a value.