section
16
16.3
The course lengths shall be given as the length of the
straight line from the start via the controls to the finish
deviating for, and only for, physically impassable
obstructions (high fences, lakes, impassable cliffs etc.),
prohibited areas and marked routes.
16.4
The total climb shall be given as the climb in metres along
the shortest sensible route.
Appendix 2
3.11.6 Courses that are not too physically demanding.
Courses should be set so that normally fit competitors can
run over most of the course set for their level of ability.
The total climb of a course should normally not exceed 4% of
the length of the shortest sensible route.
Suggests that you should measure courses two ways - one for
the length figure, and another, probably longer (and not
actually published!), for the climb limit.