After you have created the top-level context (A-0) diagram, you can decompose its Function/Activity with a child constraint diagram. The constraint diagram is a child IDEF0 diagram that can either be created or attached.
Prerequisite
Ensure that the IDEF0 diagram and definition set has been turned on for the encyclopedia.
Procedure
1 To open the System Architect Property Configuration dialog box, click Tools > Customize Method Support > Encyclopedia Configuration.
2 Select IDEF0 and IDEF3; click OK; and then reopen the encyclopedia for the change to take effect.
3 In the diagram containing the Function/Activity symbol to decompose, right-click on an symbol; then select Child Create.
The Child Create dialog box opens showing the name of the symbol on the parent diagram and the diagram type of the parent diagram highlighted in the list box.
4 If you do not want to use the name of the object symbol on the parent diagram as a name for the child diagram, type a new name in the Name field.
You can change these values; however, to conform with the IDEF0 specification, it is a best practice to accept the default values.
5 Click OK; when prompted to save the parent diagram, click Yes.
The child diagram is created.
6 When prompted to save the A-0 diagram, click Yes.
In the Child Diagram/IDEF0 dialog box, accept the default value of 4 activities or enter the number of activities for the child diagram.
7 Click OK.
You can begin drawing UOB symbols and ICOM arrows. You can free-hand draw or specify the Automatic Geometry mode.