Hey cool pic General that is interesting wish I knew but can I make a best guess and see if I'm right, bet ya Ooost will have the answer.
Anyway I reckon its got something to do with the compounds obivously, They are running triple compond tyres these days leftside/center/rightside. this been PI and the lefthand side of the tyre its the side that gets worked hardest, so perhaps Michelin have found a better way to get durabilty and grip by mixing the componds like that in sections. It kinda makes ya think of an F1 wet tyre they say the blocks on those move around to generate heat maybe a similar principle here.
Well thats my idea of it. Now I'd really like to find out what it is.