To get the field to be indexed, you may need to change the field into a text field and use a trigger controlled script to update the field when a value in the other record is changed such that the value needs to change from true to false or the opposite.
Which field should I change to a text field? Mode is a calculation field that returns a text value ("True" or "False") based on the formula given or the D_End is the field that needs to be a text field type?
My problem is that since I need to have D_End to be indexed so it will return the value of H_Depth but it keeps on reverting D_End to a Unstored because Mode is unstored calculation.
Therefore changing D_End to a text field that is updated by a script when one of the fields that determines the value of D_End is modified is one way around this limitation.