Structure of an indirectly-nested sub-formula

Here is how indirectly nests sub-formulas are treated in Optiva. An item is added to the formula. The item has an associated formula.

An item can be associated with more than one formula. One formula can be designated as the master.

Suppose the master is the sub-formula that is used in the parent formula. Another formula becomes the master. In this case, the sub-formula in the parent formula changes to the new master.

Adding an item with an associated formula indirectly nests the formula.