We think that patterns are a suitable framework for expressing the structure of N-expressions, because: (a) N-constituents cannot be replaced by any other constituent, so a literal description is appropriate, (b) the order of constituents is not flexible and often fixed.
when a parallel corpus is used, the following two types of constituents need to be considered as C-constituents: (1) the constituent to which there is a semantically corresponding constituent in the English expression, (2) the constituent to which there is no corresponding constituent in English, but deleting  A pattern description language was designed to achieve the following aims: a) patterns can be semi-automatically generated from the result of morphological analysis of a parallel corpus, and b) patterns can be defined according to the degree of generalization.