That's so they are tubeless, you can't insert nipples the "normal" way due to not having the holes on the top side of the rim.

What you've got is a Mavic 823 sprayed yellow with Dee Max stickers on. They're great rims - use them myself actually on my M1.

And yes they are a pain in the ar@e.

You can buy the tools for them (or borrow from a freindly bike shop). Best thing to do is plan an evening in with a few tins and watch a good film wihle fitting them as it gets rather tedious.

Remember to locktite the threads, oh, and use 16mm nipples.

Have fun 

Chris