P (position angle of the solar north pole) tells you how far the Sun’s rotation axis is tilted from celestial north — essential for orienting sunspot sketches and photographs. B₀ is the heliographic latitude of the disk center: when positive, the Sun’s north pole tips toward us, revealing more of the northern hemisphere; when negative, the southern hemisphere is favored. L₀ is the heliographic longitude of the central meridian, advancing ~13.2°/day as the Sun rotates — use it to track sunspots across successive days. The Carrington rotation number counts complete solar rotations since November 1853; Rotation % shows how far through the current rotation we are.