i don't know what the official word is, but i would recommend whatever exercise you want to do, take it easy and see how your body reacts.

I had abdom muscle seperation, so no exercise for me yet (just physio), but everyday actions remind me that i had a bub only recently. You still have relaxin (the hormone that allows your pelvis to open up) in your system and so are at risk of over stretching things if you go too hard.

Walking is probably the best exercise for a few weeks.