What colour flashing lights does a pilot vehicle have?

New Zealand road rule regarding pilot vehicles for vehicle convoys:

For large loads, the first pilot vehicle will use yellow lights; for extra-large loads (width exceeding 5 meters), it will use both yellow and purple lights. The second pilot vehicle will use yellow lights if the width does not exceed 5 meters and will display a "Wide Load Follow Me" sign. For loads wider than 5 meters, both the second pilot vehicle and the trailing pilot vehicle will use yellow and purple lights. Maintenance vehicles will use flashing yellow lights, police vehicles will use red and blue lights, while fire trucks and ambulances will use red lights.