33. When felling:
(a) a tree which has a felling cut already started or a tree which is retained during its fall shall never be left standing;
(b) the tree retained during its fall shall not be cut;
(c) in the cases mentioned in paragraphs a and b, the tree shall be freed by a skidder or other means of mechanical or animal traction; and
(d) a tree which supports another that is already cut shall never be felled.