A main volunteer (names in bold) is the lead volunteer responsible for that opening or closing slot each week for that half of the season. If they can’t do it one week, they arrange cover with a backup or another trained volunteer.
A backup volunteer (names not in bold) is someone who can help on that day if the main volunteer needs cover or wants to swap.
A casual / relief volunteer (names in the Casual relief section below) can sometimes help when available, but isn’t responsible for a regular slot.