Start a series at a given number — forwards, for a tenant carrying a register in from another system, or back as far as…

Start a series at a given number — forwards, for a tenant carrying a register in from another system, or back as far as one above the highest number a record still holds, for a register whose records were deleted. A deleted record’s number counts as free only where the register lets a new record reuse it. Going back is refused on a series that counts per site or category.