The first step in drawing an IDEF0 model is creating the Context or A-O Diagram. First you should have an idea of the model that this IDEF0 Context diagram will represent. You can create a model before hand, or create one as you start the IDEF0 diagram. To create a Context diagram:
1 Make sure that the IDEF0 diagram set is enabled. Select Tools, Select File, NewDiagram, IDEF0 , and type in the name of the diagram (this is one of many standard ways to create a new diagram in System Architect). Click OK. The IDEF0 dialog appears.
2 Toggle on the Context Diagram checkbox. The number of activities on the diagram is automatically limited to 1.
3 In the Model Name field, type in the name of a new model or click the Choices button and drag-and-drop in an existing model name. If you type in the name of a new model, you can optionally click Define to define the model. You can also do this later.
4 Click OK to close the dialog and create the IDEF0 diagram.
As the new diagram is created, a symbol representing the model is added to the diagram in its lower-left-hand corner.