When you create a child IDEF0 diagram, untunneled ICOM Arrows of the parent diagram are carried over to the new diagram. They are not, however, automatically attached to any Operational Activities; you must do this manually.
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.
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.
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.