Official Policy on Inactive Nations on the Map?

I was just curious if ever there was an official policy from the powers that be on inactive nations still on the map. From just a couple of quick searches, I was able to find a few nations that have expired on NS as well as having been inactive on the forums for 3-6 months.

I know there was a thread on this not too long ago, but it seemed to have died without any official conclusion. Is there an official policy, and if so, what is it?

Thanks.

Inactives may be removed on request or if someone else wants their plot as a sovereign (not gray) territory. Those with historical importance (Trioni, Paxman, and anyone with significant RP involvement) will not be removed.