In one example, a method includes defining one or more curtains, each of which corresponds to a respective one or more designated points in time, using a calendar that is common to all of the curtains, defining one or more backup policies, defining, for each of the one or more backup policies, a respective set of one or more rules, associating each of the one or more backup policies with a respective curtain, and applying, to a backup version whose currency span includes one of the curtains, one of the backup policies that is associated with that curtain.