Templates are used to capture the knotting and linking patterns of periodic orbits of positive entropy flows in 3 dimensions. Here, we study the properties of various templates, especially whether or not there is a bound on the number of prime factors of the knot types of the periodic orbits. We will also see that determining whether two templates are different is highly nontrivial.
Sullivan, Michael C. "The Prime Decomposition of Knotted Periodic Orbits in Dynamical Systems." (Mar 1994).