A subrange type is defined in terms of another ordinal data type. The type specification is:

where lowest_value < highest_value and the two values are both in the range of another ordinal data type.

For example, you may want to declare the days of the week as well as the work week:

   type
      DaysOfWeek = (Sunday, Monday, Tuesday, Wednesday, Thursday,
                    Friday, Saturday);
      DaysOfWorkWeek = Monday..Friday;

You can also use subranges for built-in ordinal types such as char and integer.