Related to Fix Patent Number Tagging system or abandon it, Stack Exchange's taging system automatically kills single use tags after so many months (unless they're added to more than one post). That doesn't make sense for Patent numbers (IMO) as it'd make it hard to find items if only a single question is posted about them.
This hasn't been a problem yet since the site is young but it should be addressed before the auto-culling starts killing single-use tags.
