From the Document: "The Terrorist Identities Datamart Environment (TIDE) is the US Government's central repository of information on international terrorist identities. The Intelligence Reform and Terrorism Prevention Act of 2004 established NCTC [National Counterterrorism Center] to serve as the 'central and shared knowledge bank on known and suspected terrorists and international terror groups.' TIDE, which contains both classified and unclassified information, is that knowledge bank. It supports the US Government's various terrorist screening efforts by supplying identities to the classified Terrorist Screening Database (TSDB), which resides in the FBI-led Terrorist Screening Center (TSC). The TSDB, commonly referred to as 'the Watchlist,' supplies databases 'downstream' with identifiers used for screening."
Office of the Director of National Intelligence: http://www.dni.gov/