PC - Point of Curvature, defines the beginning of a curve (the point of curvature for a curvilinear feature).
PT - Point of Tangency: defines the end of a curve (the point of tangency for a curvilinear feature).
You can not begin a line on a tangent curve. If a curve is either tangent (in) or tangent (out) you only need two points to define the curve.
CF - is for Curve Fit, the curve will not go through the points taken on the field but will do a best fit curve
They are for Eccentrics:
UD - means add or subtract value to the final elevation (+ means add to, - means subtract)
LR - means move point left or right by distance value (from instruments perspective ) (+ right, - left)
FB - means add subtract horizontal distance value (+ means add to, - means subtract)
UD*-2.00 means subtract 2 feet from the final elevation
LR*-2.5 means move point left 2.5 feet (perpendicular to the instrument-prism target line….from instrument perspective)
FB*2.0123 adds this amount to the final hz distance