The selected answer to this question refers to the applicability of part 23 to aircraft of nine passengers or less. Other countries certified the 208B with as many as fourteen passenger seats, using a waiver to allow the extra seats while relying on the FAA nine seat single engine certification base. The FAA normally required aircraft with ten to nineteen seats to be multi-engine.
The part 23 rewrite allows certification using ASTM standards, which provides for "level 4" occupancy of up to nineteen seats, and has a propulsion matrix with space for level 4 single engine aircraft. If the 208B were certified using the ASTM standards, would it still require a waiver to operate with more than nine passengers outside the US? Would it now be legal to operate this way inside the US under part 135?