This is a U.S. General Services Administration Federal Government computer system that is "FOR OFFICIAL USE ONLY." This system is subject to monitoring. Individuals found performing unauthorized activities are subject to disciplinary action including criminal prosecution.
Wikipedia mentions this term, but it refers to unpublished documents.
These websites are freely available (no IP, login restrictions) and often contain the same data as government websites without this note, like fbo.gov.
What are the implications of this note in the context of such public websites? What license agreements apply in this case?