18.6 Decimal Scalar String Descriptor (Packed Decimal
          String Descriptor)
  A single descriptor form gives decimal size and scaling
  information for both scalar data and simple strings. See
  Figure 18-8 for more information.

  For packed decimal strings, the length field contains the
  number of 4-bit digits (not including the sign). The pointer
  field contains the address of the first byte in the packed dec-
  imal string. The scale field contains a signed power-of-ten
  multiplier to convert the internal form to the external form.
  For example, if the internal number is 123 and the scale field
  is +1, then the external number is 1230.