Diametrical True Position with Zero Tolerance

Hello,

I have just ran across a drawing with a diametrical true position tolerance of "0" (zero), with an M with a circle around it right next to it (for MMC). In the rest of the feature control from, it has an "A", then a "B" with MMC, then "C" with MMC. Datum A is a face, Datum B & Datum C are holes that are the same as what is being toleranced (there are twelve holes). The diameter tolerance of the hole is 8.5mm +1mm/-0mm.

I'm not the greatest GD & T guy (hence, the post), soooo does this mean I would only get tolerance if I held the diameter larger than 8.5mm because of the MMC callout? I am trying to determine the machining process for this part and need to know how feasible this tolerance is to hold...or what tooling/size I should use/try to hold. If I held the diameter at 9.2mm, how far could I be off from the mean dimension? I've never seen a "0" for a true position tolerance....

Thanks for any help.