A 12-lead has 2 windings for each phase. It could be part winding started when these 2 windings are in parallel. This would me it's possible in the low voltage connections since the winding are only in parallel for the lower voltage. Even though the data typically only calls out a wye-delta type start with a single lower voltage, there are actually 2 voltages where it would be possible. For example, with a 230V/460V motor, a part winding start is possible at 230V delta or 400V wye. Obviously, the 400V wye connection likely won' be much use in North America where 480V is the common voltage.