Should mementos be used instead of (or in addition to) Timestamps?

This page has been created to capture the argument from AggregatorBehaviorRules of whether a Memento would be better to use than a Timestamp in delta updating. The general consensus is that Timestamps are best, Mementos are not needed.

A memento/cookie system? The client makes a request. The server returns the result + a memento/cookie. The next client request includes the memento/cookie and the server knows only to return changes made "after" whatever the memento/cookie refers to. The memento/cookie has meaning to the server, but is an opaque string to the client.

[AsbjornUlsberg] I just want to mention that my proposal on the [WWW]"extended search" can make it fairly easy to retrieve entries since I'm not sure wether this helps this discussion, but I felt it was worth mentioning.