...
A website manager is asked to change all the links on a site to PID's. He or she can follow a defined workflow for assigning PID's to links, for modifying location references, and for replacing referenced URL's with PID's.
We need a solution for legacy websites incapable of being modified to store the PIDs created; the resolver must be able to assume that the original URL provided for the resource will continue to function, or that some alternative will be provided when the legacy website ceases to respond. This becomes a matter of policy rather than technology.