An Army-specific Blue Force Tracking technology is Force XXI Battle Command Brigade and Below, or FBCB2. The system continually transmits locations over the FBCB2 network. It then monitors the location and progress of friendly (and enemy) forces, and sends those specific coordinates to a central location called the Army Tactical Operations Center. There the data are consolidated into a common operational picture, or COP, and sent to numerous destinations, such as the headquarters element, other in-theater forces, or back out to other military units for situational awareness. The system also allows users to input or update operational graphics (i.e. obstacles, engineer reconnaissance on the road, enemy forces). Once uploaded, it can either be sent to higher headquarters or "mailed" to other subscribers of that user's list, or other BFT users within the subscription system. The M1A1 Abrams's tank AIM refurbishment/upgrade program includes FBCB2 and Blue Force Tracking.