The next method of corner restoration which will be considered
is the three-point control method. The following section describes
what it is, where it is used, and how it is computed.
Three-point control is used in situations where known corners exist
in only three directions from a lost point. The fourth direction
was never surveyed, so it is impossible to use an original corner
for a proportionate four-way control in that direction.
In such a situation, Section
5-29 of the manual states: "Where the line has not been
established in one direction from the missing corner, the record
distance will be used to the nearest identified corner in the opposite