To consider the addition of general purpose transformers 600 volts and below to C57.12.01. NEMA standard St-20-1992 and UL-1561 reference C57.12.01 in their respective standards. To consider the addition of general purpose transformers 600 volts and below to C57.12.01. Revision Standard - Superseded. Superseded by IEEE Std C57.12.01-2005 Electrical, mechanical, and safety requirements of ventilated, nonventilated, and sealed dry-type distribution and power transformers or autotransformers, single and polyphase, with a voltage of 601 V or higher in the highest voltage winding, are described. Information that can be used as a basis for the establishment of performance, interchangeability, and safety requirements of equipment described, and for assistance in the proper selection of such equipment, is given.