Bow/edge/bell notes with the pedal in the open position are taken from the HiHatB/E settings.
Bow/edge/bell notes with the pedal in all other positions are taken from the HiHat Pedal settings (BowSO/EdgeSO/BellSO/BowHO/EdgeHO/BellHO/BowSCL/EdgeSCL/BellSCL/BowCL/EdgeCL/BellCL).
This is needed if the sound software/sound module doesn't support CC04 for pedal positions.
If the the sound software/sound module supports CC04 for pedal positions than BowSO/EdgeSO/BellSO/BowHO/EdgeHO/BellHO/BowSCL/EdgeSCL/BellSCL/BowCL/EdgeCL/BellCL should be equal to bow/edge/bell notes in the HiHatB/E settings and the sound software/sound module should take care of modifying HiHat sounds based on CC04 messages. How it is done in SD2 I don't know.