Universal?
This seems to be the meaning:
http://www.freerepublic.com/focus/chat/3674854/posts?page=700#700
my best guess so far is it relates to a level of security clearance. As in when POTUS declassifies it And it goes from C classified to U unclassified they are done..
An
Unclassified (U) is a valid security description, especially when indicating unclassified information within a document classified at a higher level. For example, the title of a Secret report is often unclassified, and must be marked as such. Material that is classified as Unclassified // For Official Use Only (U//FOUO) is considered between Unclassified and Confidential and may deal with employee data.