White is white, yellow is yellow, and chartreuse is NOT yellow. If it has a greenish tint, it is NOT yellow. If it is "pale yellow", it is not YELLOW. Similarly, if it is beige, cream or ivory, it is not WHITE.
Colors other than plain YELLOW can be very difficult for cornerworkers, scorers or other officials to differentiate when the bike is traveling at speed. I invite you to come up to the 'bridge to see firsthand the difference and importance of having the proper numbers/background on your bike.