One section of this standard presents a thorough explanation of thyristor principals, defining thedifferent classes of these devices, their Physical structure and detailing the numerous test methods and ratings required in their application to electronic and power circuitry. Another section presents a universally accepted listing of letter symbols. Considerable effort is devoted to the use of JEDEC Type Registration System as related to thyristors. This will permit the device manufacturer to employ a uniform procedure in the development of maximum rating and presentation of performance data.