It looks like I'll soon be typing CUI instead of SBU when marking official documents that contain sensitive but unclassified information.
The Presidential Interagency Task Force on Controlled Unclassified Information (CUI) has recommended the U.S. government implement 40-some changes to standardize the many and various ways in which such information is currently being designated, marked, and safeguarded.
There are now over 100 different marking schemes in use for such information - as anyone who has worked with multiple U.S. government agencies is no doubt aware - and they often mean different things to different people, leading to much confusion and frequent over-classification. This is a bad situation in general, but it has created a particular problem for the dissemination of anti-terrorism related information to local (i.e., non-Federal) law enforcement and private sector entities, and that is the problem the task force was charged with solving.
Secrecy News has some comments on the recommended framework (here), which they think may have too lax a definition and be too vague regarding eventual release or decontrol.
I suppose we'll call the new designation "Coo-eee." An improvement over SBU, which doesn't make for a pronounceable acronym, but still not as agreeable as the term the State Department used before SBU came along, which was LOU ("Lou") for Limited Official Use. To my personal knowledge, at least one security violation was given out for a note addressed to someone named Lou and found on a desk after hours by a Marine Security Guard.