On hierarchical software metrics

The notion of a hierarchical software metric is introduced, encompassing and extending the earlier work of Fenton and Whitty and this author. It is shown that a stronger interpretation of this notion is insufficient for treating the important `number-of-paths¿¿ metric, whereas this metric definitely falls within the range of the axiomatic system introduced herein. Finally, the technique of argument by induction over an arbitrary flowgraph decomposition is clarified and demonstrated in the new hierarchical context.