document updated 16 years ago, on Jan 24, 2009

Lightbulb sizes.

E12(mini), E17(small), E26(most common, 1 inch), E39(giant) — Edison screw, the number is millimeters (Europe uses the exact same system, but uses slightly different mm sizes)
B*, BA*, BY* — bayonet
G* — bipin

These are totally independent of the base code, and if you have a large bulb cavity, you may choose to ignore this code altogether.