Well well well. I only recently reported on a major change in the French definitives (see here), and here's yet another one! This is turning out to be a very nice and varied set!
I'm not totally in the know but I believe that for a long time there have been green definitives, representing a slower, surface mail rate. Now, these green definitives have become properly green.
I love the design, think it's quirky, and I like the idea behind it. And it's a perfect sideline in a collection of this set.
And what's even better: instead of the one green stamp which we used to have, the green stamp is now available for four different weight rates, in four different shades of green.