Package Merge   A package merge is a directed relationship between two packages that is used when elements of one package (tail end) represent the same concept as those in another package (arrowhead end). It is a convenient way of representing a set of generalizations and redefinitions between two packages. It is termed a merge because the relationship means that elements with the same name and of the same type from one or more packages will be merged into a single element in the merging package (tail end). This is achieved by the use of generalizations and redefinitions.

Explanation

A package merge is a convenient way of expressing that the elements of one package represent the same (or similar) concept as those in another package. It represents a set of transformations where elements of the merged package (arrowhead end) will be created in the merging package (tail end). There are a series of rules that govern whether an element will be created and the generalization relationships and redefinitions that will be used in its definition. If an element is private in the merged package it will not be created in the merging packing. A classifier in the merged package will be created if it does not exist in the merging package. Either way, the newly created classifier or the existing one in the merging package gets a generalization relationship to the classifier with the same name in the merged package. If there are a number of packages that contain classifiers of the same type and name, a single element is created and given relationships to each element in the respective packages.