On representation of a stable element of a free nilpotent group

In order to find a nontrivial stable element of a free nilpotent group, it is necessary to isolate all possible types of basic commutators that are later used to build a candidate for a stable element. The article is devoted to the description of three kinds of switches; each of them is closely related to the other two. For example, if the representation of a stable element includes commutators of one of the types, then the remaining species must be represented in the expansion of this element. We consider a free nilpotent group of rank 3 and of order 12.