When iteratively building a program (revise/activate/deactivate/revise), it is not possible to delete elements from the program after it has been deactivated, nor can orphaned (detached) elements be deleted (as when temporarily out of view after the space has been repositioned). However detaching/repositioning/reattaching are allowed.

Another option worth considering: allow programs to invoke data source maintenance tasks, whereby the maintenance tasks are define like programs and invoked by programs.