National Electrical Manufacturers Association (NEMA) reaffirmed ANSI C78.1406-2004 American National Standard for Electric Lamps—P28 Single-Contact Medium Prefocus-Based Projection Lamps for Base-Down Operation—Dimensions, which is available via downloaded and in hard copy. Developed by Accredited Standards Committee for Electric Lamps, said standard establishes dimensions essential to interchangeability of single-contact medium prefocus-based projection lamps of T10 and T12 bulb sizes.