What does this mean (green pony reinstatement)?

If you do less than three shows at the 2'3" height during the previous competition year, you can keep her green status during the next year but no longer. Since the competition year starts May 15th, then that is the date given. So, from May 15th, 2010 to May 14th 2011 she can't do more than 3 shows over 2'3" in order to have her green status reinstated. The next year, you can't.