"AF Range" button on A99

I went through the leaked A99 pictures on sonyalpharumors. I noticed a button on the back which is labelled "AF Range". Granted this is rumor and for all we know, there might not even be an A99 in the making

Still, for now, I believe what they show there. So, what is this button for? Is this going to put a Focus Limiter button on all of your lenses? Thus making my Tamron 70-200 focus faster?

What do you think?