It appears possible to extend the application of most of the existing detection techniques to the identification and separation of charged particles in the relativistic energy region. One can probably extend these applications, in certain limited cases, up to an energy region of several hundred billion electron volts. However, for general applications in the identification of particles in the ultrarelativistic region, the existing detectors are rather limited, and new methods and approaches are desirable. At present, detectors making use of the relativistic rise effect seem to show considerable promise.