P = point under consideration
F = foot of perpendicular from P to the central meridian. The latitude of F is called the footprint latitude.
O = origin
OZ = central meridian
LP = parallel of latitude of P
ZP = meridian of P
OL = k₀S = meridional arc from equator
LF = ordinate of curvature
OF = N = grid northing
FP = E = grid distance from central meridian
GN = grid north
C = convergence of meridians = angle between true and grid north

Just so you know what you're getting yourself into...