Ordinal types are a subset of the simple set other than real
      and are set off by these characteristicis:

      The standard function ord can be used on any ordinal type to
      return the  ordinallity of the value.

      The standard function Pred can be applied to any ordinal-type
      value to return the predecessor of the value.  If applied to
      the value in the ordinal type, Pred produces an error.

      The standard function Succ can be applied to any ordinal-type
      value to return the successor of the value.  If applied to the
      last value in the ordinal type, Succ produces an error.

      The following are ordinal types:  integer, shortint, longint,
      byte, word, boolean, char, enumerated and subrange.