Style #12
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Constraints:

- The larger problem is decomposed into types of 'things' that make
  sense for the problem domain

- Each type of thing is described by what operations the things of
  that type can eventually do

- Concrete things are then bound, somehow, to the types; mechanisms
  for doing that vary

- The rest of the application uses the things not by what they are but
  by their types

Possible names:

- Types of things
- Abstract data types