IDEF0 as a method requires lines to be balanced between parent activities and child diagrams. For example, if an input is added to a parent activity then it is required to be added to the child diagram of the activity, or if an output is added from a child activity it is required to be added to the parent symbol.

When you add, delete, tunnel, or disconnect ICOM arrows on OV-5 diagrams, System Architect will auto-balance the parent and child OV-5 diagrams. You are presented with a dialog of choices on how to balance the diagrams.

When you make a selection, the process is automatic and transparent to you — not something you have to manually refresh the child diagram to see. The following sections provide detail on this behavior.

By toggling on Full Grand Parent/Child, automatic balancing works not only for the immediate parent or child diagram, but all grand parents or grand children to that diagram, as long as they are open.

By toggling Don’t Ask Me This Question Again, automatic balancing is performed without the IDEF0 Balancing dialog coming up.

When you add an ICOM Arrow to a Operational Activity symbol on a parent OV-5 diagram, System Architect automatically adds a similar ICOM arrow of the same name to the diagram workspace on child OV-5 diagram. The arrow is added to the appropriate side of the diagram (input arrows on the left, controls on the top pointing down, mechanisms on the bottom pointing up, outputs on the right pointing right), but not attached to any child Operational Activity. This holds true for Input, Control, Output, or Mechanism (ICOM) arrows, but not for Call arrows.

In the example below, adding an input ICOM arrow, named Input 1, to a Operational Activity symbol, named Parent Activity, on a parent OV-5 diagram automatically adds it to the diagram workspace of the child OV-5 diagram, on the left side of the workspace.

In System Architect you can specify that an ICOM arrow be tunneled: select Tunneled (Parenthesis) in the arrow's associative dialog (one way to open this dialog is to right-click the arrow and choose Associative).

When adding a new ICOM arrow to a parent diagram, System Architect's auto-balancing functionality takes into account tunneled arrows. If you add an ICOM arrow to the parent diagram that has the same name as a tunneled ICOM arrow already existing on the child diagram, then System Architect will untunnel the ICOM arrow on the child to make the lines consistent (toggle off the Tunneled (Parenthesis) property in the line's Associative dialog).

When deleting an ICOM arrow from a parent Operational Activity, you are presented with a set of choices on what action to take on the child(ren).

In the dialog box above, for example, you can select:

Non-Deletion of Local Arrows on Child Diagrams:

If a line is deleted from the parent diagram, and the name of that line also appears as a local arrow on a child diagram, or a grandchild diagram, the local arrow is not removed. Only the arrows and arrow segments immediately attributable to the deleted line are deleted.

For example if an ICOM arrow named Input 1 is deleted from the parent diagram, in the child diagram the line Input 1 that goes into Operational Activities 2 and 3 is deleted; the local arrow from Operational Activity 1 to 2 is not deleted.

You can make an existing ICOM arrow tunneled (by accessing the associative properties of the line and toggling on the Tunneled (Parenthesis) property). This has the same effect as deleting it from the child diagram. System Architect presents you with the same choices as if you were deleting the ICOM arrow from the parent. Selecting Cancel actually undoes the tunnel (untoggles the Tunneled (Parenthesis) property in the arrow's associative dialog).

Disconnecting an ICOM Arrow on the Parent Operational Activity Symbol (rather than deleting):

You cannot disconnect a line from the Parent Diagram; if you do so, this message appears:

When you add an ICOM Arrow to Operational Activity symbol on a child OV-5 diagram, System Architect automatically adds a similar ICOM arrow of the same name to the appropriate side of the parent Operational Activity symbol on the parent OV-5 diagram. This holds true for Input, Control, Output, or Mechanism (ICOM) arrows. It does not hold true for Call arrows.

In System Architect you can specify that an ICOM arrow be tunneled — by toggling on the Tunneled (Parenthesis) property in the arrow's associative dialog (one way to open this dialog is to right-click the arrow and choose Associative).

If you select a tunneled ICOM arrow on a child diagram, and untunnel it, then the line will appear on the parent diagram.

When deleting an ICOM arrow from a child diagram, you are presented with a set of choices on what action to take on the parent. You can delete it, or tunnel it.

You can make an existing ICOM arrow tunneled (by accessing the associative properties of the line and toggling on the Tunneled (Parenthesis) property). This has the same effect as deleting it from the parent diagram. System Architect presents you with the same choices as if you were deleting the ICOM arrow from the child diagram. Selecting Cancel actually undoes the tunnel (untoggles the Tunneled (Parenthesis) property in the arrow's associative dialog).

If you disconnect an ICOM arrow on the child diagram, it has the same effect as deleting the symbol: System Architect provides the same set of choices for how to balance the parent diagram. Selecting Cancel actually undoes the symbol move that caused the disconnect (it reconnects the line symbol).