Trong kịch bản theo dõi quá trình tiến hóa, sự kiện phân giới cắm mốc liên quan đến lớp NewBoundary, lớp phân định và lớp OldBoundary (Hình ). | PUBLIC BOUNDARIES EVOLUTION 71 Figure The class diagram for the evolution tracking scenario-demarcation event In the evolution tracking scenario the demarcation event involves the NewBoundary class the Demarcation class and the OldBoundary class Figure . NewBoundary represents the legal location of a public boundary. OldBoundary represents the old status of a public boundary. In other words it characterises the actual location of a public boundary after the demarcation. The Demarcation class plays an important role within the STDM. It controls the flow of operations between NewBoundary and OldBoundary. The interaction diagram in Figure uses a box to represent the relative time that the flow of control is focused in a Demarcation class. Each instance of Demarcation is the ultimate focus of control and its behaviour of carrying out a demarcation event invokes different methods over the instances of NewBoundary and OldBoundary. This is achieved by defining the following operations for the Demarcation class select confirm assign. The delimitate demarcate and select associations in the class diagrams Figures and denote a semantic dependency and suggest a bidirectional navigation between classes. They also represent the independent incremental modifications in the STDM. In the delimitation event DraftBoundary is the parent class having Delimitation as the modifier into a resultant NewBoundary class. Moreover in the demarcation event NewBoundary becomes the parent class having Demarcation as the modifier into a resultant OldBoundary class. Consequently a user will be able to select a draft boundary to be a new boundary and afterwards to be an old boundary using the independent incremental mechanism. This allows users to enter values for the properties of classes involved in the evolution tracking scenario taking into account the evolutionary aspects of the scenario. Classes are interrelated through the incremental mechanism in order to support .
