PowerPivot Nested Set Measures

In my ?Handling Flat, Parent-Child and Nested Set Hierarchies & PowerPivot Powered Budgets & Targets posts I discussed my use of Nested Sets as a means of modelling unbalanced and ragged hierarchies. My 1st instinct when confronted with a non-trivial hierarchy, flattened or not, is to reach for my trusty Nested Set builders. However it's not just as an ETL re-modelling method that a datasmith is likely to encounter nested sets, they also exist as variations-on-the-theme in production system data models. One of the most common use is in the modelling of systems' ACLs (Access Control Lists). This use of range queries (often utilising "positive ranges" MINUS "negative ranges" plus or minus "ragged lists") can be very complex and would prove difficult to model using the flattened cross-join options available in PowerPivot (point solutions by "hard coding" a fixed set of relationships are possible, but a generic "handle all comers" solution would be very difficult).