# God's Eye View Current State AIS encodes speed over ground in 0.1-knot units and course over ground in 0.1-degree units, reserving the top code of each field for "not available", so those reports arrive as 102.3 knots and 360 degrees. Both are stored as unknown, and vessel cards, the HUD and analyst queries show a missing measurement rather than a reading. Heading keeps its existing separate check for its own sentinel. Genuine readings are unchanged, including a stopped vessel's zero and the highest speed and course the fields can encode. Native `