It's a mystery to me. I only mentioned it because I have noticed a few people talking about Apple divulging channel inventory. It might make sense to them but it sure doesn't help me understand Apple's numbers any better. [this is not meant as a slight against Apple]
Speaking of channel inventory... I noticed from the q4 2012 that there was an estimated 9 million units in the channel. In the q4 2013 there was an estimated 14 million units in the channel. I'm not even sure what all that means but I'm sure it is not inconsequential.