Sub milimeter? How "sub"? (Score 1)

I heard about another(?) theory proposing the existence of many dimensions "confined" (or somehow "tied") within a Planck space (the amount of space measured by a Planck Constant, a very, very, very small number) (I heared about this space being some kind of "quantum of space") Is this new theory (many dimensions within sub-milimeters) related with the older (many dimensions within Planck space) ???