Any pattern of working time that covers six days a week.
However, within the six days, it is not necessarily the case that all 24hrs a day are covered; or the number of hours rostered a day is constant; or the number of people present on each rostered shift is the same.
The day not covered by the rota are frequently, but not invariably, a Sunday. The timing of the day off can be from midnight to midnight, but more frequently it is linked to shift start and finish times. For example, from 22.00 Saturday to 22.00 Sunday, or 06.00 Sunday to 06.00 Monday.