The Collection of All Possible DCJ Operations. The DCJ incorporates many operations, depending on the structure of the chromosomes involved and whether the adjacencies used belong to the same chromosome. (a) Operation 1 in the definition of the DCJ incorporates linear internal translocations, reversals, circular fusions/fissions, the excision of a circular chromosome from a linear chromosome, and the integration of a circular chromosome into a linear chromosome. (b) Operation 2 incorporates telomeric translocations, affix reversals (which involve the telomere of a linear chromosome), and the fission of a linear chromosome into a circular and linear chromosome (together with its inverse). (c) Operations 3 and 4 include linear fusions/fissions as well as the linearization/circularization of a single chromosome.