31. When felling (1) a notch must be used to control the direction of fall of any tree with a diameter at stump height of 15 cm or more, in accordance with the following conditions:
(a) the notch, made with an undercut and a back cut, must be made to a depth of approximately 1/10 the diameter of the tree to be felled such that the fall can be guided and controlled;
(b) the undercut must be made at a minimum 45-degree angle, to a depth of approximately 1/3 the diameter of the tree to be felled;
(c) the back cut must be made at a point at least 2.5 cm higher than the tip of the undercut;
(2) a tree which has a back cut already started must never be left standing;
(3) a tree retained during its fall must never be left standing or slashed.
In the cases referred to in subparagraphs 2 and 3, the tree must, subject to the use of an appropriate hand technique taught during the training provided for in section 27, be freed by a skidder or other means of mechanical traction.