Pentax R-200 Series Instruction Manual page 106

A B: Distance between Point A and B. This is always positive.
P A – B Distance between Int. P and P, This is positive or negative as shown below.
Int. P A Distance between Int. P and A, This is positive or negative.
−
Int. P B Distance between Int. P and B, This is positive or negative.
The arrow direction is positive.
A Int.P
−
P
+
Int.P
A
P
−
Int.P
A
P
Int.P: Intersection point
P: SOP, Stake Out Point
−
B
+
B
B
41
+