[1]A feature is a prominent or distinctive user-visible aspect of a software system. Features identified are classified as: mandatory: common to all domain's applications; optional: can be present or not in a domain application; alternative: features that cannot be contemporaneously present in a domain application.

[2]For example in the "object attributes identification" step the attribute to be identified should be searched inside all objects in a class without taking into account their source application; the "refining classes with inheritance" step has been changed in "refining classes with inheritance and aggregation" in order to share common structures and features between applications ...;