This is to be a revision of ANSI N42.3/IEEE 309 and will include within it also the material now in ANSI N42.5 on standard bases. The inclusion of the N42.5 material is the reason for including "Standard Bases" in that revised title. Upon issuance of this revised N42.5 should be withdrawn and that is the intent. The standard is nearly 30 years old and is in need of updating. Geiger-Mueller counters continue to be produced and used in quantity.