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This model has three levels. The top level has one diagram representing the structure of the activity, supply construction project, in terms of two activities, plan supplies and obtain supplies. The second level has two diagrams that represent the structure of the two activities, plan supplies and obtain supplies, in terms of four activities, choose suppliers, order supplies, deliver supplies and pay for supplies. The third level has four diagrams that represent the structure of these four activities in terms of ten lower level activities.
Note that each level takes the activities in the level above and expands them into a network of activities and interactions. It also expands some of the lines but only expands them into sets of lines. For instance the control interaction, requirements, in the top level diagram is expanded into the control interactions, supplier constraints and supply requirements, in the (left hand) second level diagram.
The control interaction, requirements, represents the constraints placed on the construction project by its customer. The customer nominates some (not all) suppliers for the project, this is represented by the control interaction, supplier constraints. The customer determines by means of engineering specifications what supplies are required by the project, this is represented by the control interaction, supply requirements.
The left hand lower level diagram expands the activity, choose suppliers. It represents suppliers providing register agencies (e.g. yellow pages) with their credentials (justifications for their roles as suppliers), the register agencies providing register entries to the construction company, and the construction company selecting suppliers.
Suppliers are asked to give quotes (estimates of cost) for supplies.
The remainder of the model should be self explanatory.
last revision: 21st June 1997