Extreme care must be taken with the map survey and the placement of the circles, the centre of which must represent exactly the placement of one of the cluster of posts. The choice of post shown by the circle centre may be varied, thus giving a series of courses.
Take control 6 for example. The circle is centred on the post to the east side of the stream at the bend. There are two other posts, one on the west side of the stream at the bend, and one on the east side of the stream to the north of the bend.
In view 1, seen from a point on the track to the North East,
the centre of the circle is the leftmost 'A' post.
View 2, seen from a point on the track the North North East,
gives an apparently different post setting although the answer
is still 'A'.
A third decision position, seen from the track to the North
is shown in View 3, in this case the answer is 'B'.
Refer back to View 1 and the map as viewed from the North. If the circle were now to be centred on the northern 'C' post a further set of answers would be available.
The choice of control circle and viewing point can be repeated for each set of markers posts, giving a variety of courses using the same posts.