Timestamp updates

It would be useful if it could be told when a particular variable was last updated. I am thinking about adding a timestamp in the major and/or minor labels. Things to consider are
1. If a label has more than one variable, the timestamp would probably be the time of the most recent update for any variable in the label.
2. Does it count as an update if the variable is set the the same value that it is already set to? In other words, if your ~garage_door~ variable is already set to OPEN, and you receive an update, again setting it to OPEN, then should the timestamp remain unchanged, or should it reflect the latest update?
3. Where and how to display the time. Perhaps use a special tag so that the user can decide how to display it. The benefit here is that that user can decide whether or not to use the timestamp.

Cancelling because I have thought about this a little more. If a particular variable needs to have a timestamp saved with it, then the timestamp should be sent from PH and stored in a separate variable within PHCA.