Your career manager at HRC can tell you, and there's usually someone at your local S1 shop that can too. Hopefully, those people in your life are more useful than they were for me. I couldn't get my career manager to return my emails, much less pick up the phone, until I contacted my consultant and asked him to intervene. When I asked the civilian personnel person from S1, he told me that he couldn't tell me when my obligation was up if I didn't already know.
HopefulPilot is right; that box on your ORB is meaningless. Much different than on an ERB, as I understand it.
An Air Force colleague once showed me a website where he could see the end of his contract(s). Not surprisingly, the Army had no such mechanism, as they prefer obfuscation.