Update:
When I got back in the shop, my mechanic showed me how easy it was for the sticker to come off. He also made a comment that the "dealer parts" guy are not mechanics can not confirm through BMW. e.g., He was basically saying the "parts guy" don't know what they are talking about as he claims 100% certainty that all E90's are suppose to be CHF-11S for power steering.
Anyways, he is a respected indy BMW mech here in Toronto... so I am reassured.
***Unless someone on this board can confirm that they bought their E90 brand new with the ATF permanently etched on it without any sticker over it, then the assumption is that all E90's are required to be CHF-11S for power steering.
If you bought your E90 second hand and your reservoir cap says ATF on it, the sticker could have came off.
Bottom line, if you are unsure, look at the fluid that is in the reservoir itself...
I don't know the visual difference between ATF and 11S fluid
, so if someone can bullet point the difference out, that would be helpful for others.