Requiring fine-grained capabilities

The current specification allows the capability for a collection to be used when accessing an individual member of that collection, which is a violation of the Principle of Least Privilege. Of course, the holder of a capability for a collection can always create a new capability for the individual item, but that requires extra work that many people won't do. The result will be that a successful attack will be able to do substantially more harm than had the system required fine-grained capabilities.

It should be possible for the software invoked when submitting a request to construct the fine-grained capability from the one provided by the invoker.