The first step in drawing an IDEF0 model is creating the Context, or A-0, diagram.
Prerequisite
1 Make sure that the IDEF0 diagram and definition set has been turned on for the encyclopedia. Select Tools, Customize Method Support, Encyclopedia Configuration to open the System Architect Property Configuration dialog box.
2 Select IDEF0 and IDEF3, and then click OK
3 Reopen the encyclopedia for the change to take effect.
You should have an idea of the model that this IDEF0 Context diagram will represent. You can create a model before, or create one as you start the IDEF0 diagram.
Procedure
1 Select File > New Diagram > IDEF0.
2 Type a name for the diagram; then click OK.
3 In the IDEF0 dialog box, select Context Diagram.
The number of activities on the diagram is automatically limited to 1.
4 In the Model Name field, type in the name of a new model or click the Choices button and drag 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.
5 Click OK.
As the new diagram is created, a symbol representing the model is added to the diagram in its lower-left-hand corner.