While structural object-orientation is not
very useful without operational objectorientation,
both (b) and (c) are within the
range of object-oriented database systems;
note that the scope is thus broader than with
object-oriented programming languages
which are concentrated on the paradigm
sketched in (c) only. However, there seems
to be agreement that even the (somewhat less
advanced) operational object-orientation is a
versatile solution for database systems (and
might at least be used as a basis for the
internals of abstract data types in (c)). By
the way, concepts like property inheritance
may be added to both (b) and (c).