SOX has been always confusing me if it's HID or Fluorescent. I'd say they're both but it's probably one of these two options.
Questions why I think it's HID or Fluorescent:
1) SOX uses a Discharge tube, just like most of HID bulbs do
2) SOX is literally as long as fluorescent tubes and most of fluorescent lights are long
So, any clue if SOX is HID or Fluorescent?
Neither.
No fluorescence is in use and not high intensity arc

Lamp behavior, physical parameters and drive requirement are somewhat close to fluorescent tubes, sure.