The method of the operation path on the generalized ignition contour map () is used to treat the ignition accessibility of a deuterium-tritium tokamak reactor for different types of confinement scaling including offset linear scaling. It is shown that the operation paths and ignition boundary on the plane as well as the nτE-T plane provide a useful ignition criterion for various types of scaling. The International Thermonuclear Experiment Reactor (ITER) tokamaks with low and high toroidal fields are used as examples.