• Criterion_i: These classes represent each one of the alternative abstraction criteria of the TargetDomainConcept (Criterion1, Criterion2, Criterion_i in the Figure above). The list of classes may not be exhaustive or pairwise disjoint.

• Ci_Class_x: These classes refine each abstraction criteria class (C1_Class1, ..., C2_Class1, ..., Ci_Class_i in the Figure above). The list of classes may not be exhaustive or pairwise disjoint.

• CiClass_xCjClass_y, Ci_Class_xClass_y: These classes participate in multiple inheritance relationships combining different refinements from the alternative abstraction criteria classes (C1Class3_C2Class2 and C1_Class1Class2 in the Figure above).

• A first criterion can be derived from the left column of the matrix (listing the basic view points from Figure 2: Development/Operational Faults, Internal/External Faults and so on). This column represents the values of the eight basic viewpoints which lead to the elementary fault classes.
• A second criterion can be abstracted from the bottom row (listing numbers 1 to 31). This row represents the 31 likely combinations of fault classes out of the 256 possible.
• A third criterion is implicit at the top row, representing the three major partially overlapping groupings of faults: Development, Physical and Interaction.
• A fourth criterion can be seen at the bottom row, labeled Examples, containing nine illustrative examples of fault classes.

There is an interesting feature regarding the types of multiple inheritance relations that can take place in the context of a View Inheritance pattern. These types of multiple inheritance relationships can be characterized as:

• Inter-criterion, when the parent classes involved in the multiple inheritance relation are subclasses of different abstraction criteria. The class C1Class3_C2Class2 in Figure 1 is an example of this type of inheritance because one of its parent classes, C1_Class3, is a refining concept of Criterion1 and the other parent class, C2_Class2, is a refining concept of Criterion2.
• Intra-criterion, when the parent classes involved in the multiple inheritance relation are subclasses of the same abstraction criterion. The class C1_Class1Class2 is an example of this type of inheritance because all of its parents classes, C1_Class1 and C1_Class2, are refining concepts of the same criterion, Criterion1.
• Intra- and inter-criterion, when there are at least two parents involved in the relation that are subclasses of the same abstraction criterion and there is at least one more different parent that is a subclass of a different abstraction criterion. An example of this type of inheritance is trivial to extrapolate from the composition of the previous two.

• Rector, A.L.: Modularisation of domain ontologies implemented in description logics and related formalisms including owl. In: K-CAP '03: Proceedings of the

2nd international conference on Knowledge capture, New York, NY, USA, ACM (2003) 121--128