Drawing ICOM arrows on NOV-5 context diagrams for NAF
On a context diagram, you can draw Input, Control, Output, or Mechanism (ICOM) arrows from blank space into the single operational activity symbol on the diagram. You can draw output ICOM arrows from the operational activity symbol into blank space. The same ICOM arrow tool is used to draw all four types of lines.
1 In an open Activity Model diagram, on the Draw toolbar, select the ICOM Arrow tool.
2 Draw the arrow from blank space to the side of the operational activity symbol into which you want the arrow to go, following the ICOM arrow rules of placement.
Note To show iterated activity in an IDEF0 child decomposition diagram, draw a call or output arrow exiting from a function or activity symbol, then loop back to that same box as an input or control. You must use the Straight (orthogonal) line style to loop ICOM Arrows. To set line style, right-click a previously drawn ICOM Arrow; then click Format > Line Style > Straight (orthogonal).
3 Name the ICOM arrow; then click OK.
4 To tunnel the arrow, in the Associative Properties dialog box, select the appropriate Tunneled (Parentheses) check box.
Note When an arrow into a box is tunneled, it means that the data associated with the arrow does not need further understanding (or need to be modeled) on the next-level child decomposition IDEF0 diagram. The System Architect modeling software does not automatically add tunneled arrows to a child IDEF0 diagram.
5 Click OK.
The graphic below illustrates how ICOMs are used with a single function. The Operate Warehouse function takes Customer Order as an input, uses Inventory and Customer as Controls, uses Materials Management and Carrier as Mechanisms (mechanisms can be thought of as “resources”), and has outputs of Purchase Orders, Shipments, and Order Confirmations.
Mapping ICOM arrows to child diagrams for NAF
When you create a child IDEF0 diagram, untunneled ICOM arrows from the parent diagram are carried over to the new diagram. You must then attach the ICOM arrows to operational activities.
To attach a parent arrow to an activity
1 Select the parent arrow and drag the line to the activity at which you want the line to end. A cross appears at the end of the line to show that it is attached.
2 Release the mouse button.
An IDEF0 diagram can have more than one of each type of ICOM arrow. Any output arrow can provide input, control, or mechanism data to one or more boxes. The child diagram also shows the constraining relationship of arrows, that is, a function that receives input or control from a previous function is constrained by that previous function.
An unconnected end of an arrow, in a child diagram, must have the ICOM code to specify its connection to the parent diagram or it must be tunneled.
Note Deleting an arrow from a child diagram does not delete it from the parent activity. The arrow on the parent will be tunneled the next time the parent diagram is opened.
