From Bryan Uy on 5/22/18:
Having an option (n CNTLS(SPLAN)?) to completely replace activity editors with custom XML will be useful for clients that need a lot of customization on their AE. I am thinking that it’s best to have an AECTL type of entry where for some TYIs an Activity Editor is suffient but some could be XML. One big advantage for XML over AE is that we can embed a work process in the GUI itself rather than rely on checks in $PBBEF or $PBAFT to accept or reject user actions. As an example, I can have several modifiable fields but some of them could be in conflict (user changes both rate and duration) and we tend to handle them after user clicks OK or apply. With XML, I have control on disabling some inputs depending on where the user starts from. Another advantage is that we have control over layout (not just vertical).
S MODIFY needs to change to take this into account