A slight example of bad grammar in the UL white book on the meaning of the markings.
What they 'meant' to say was:
"SWD" means that the breakers can switch the worst, most demanding type of lighting that existed at the time: fluorescent. They can switch 'ordinary' lights as well. When lighting companies then went out and made an even worse type of light (HPS, the MH) ... we had to come up with the "HID" rating to cover those. Praise heaven that the latest lighting innovations (cold-cathode, LED, etc) are less demanding than nasty fluorescents and HID's, or we'd have to come up with yet another rating!"
