To paraphrase former Secretary of Defense Donald Rumsfeld, there are known knowns, things we know we know, and known unknowns, things we know we don’t know. But there are also unknown unknowns, things we don’t know we don’t know. On his latest single, You Don’t Know About It, Boston representative (and freestyle series contributor) M-Dot and French beatsmith Jean Maron hook up with a seasoned rap vet to cast light on a few subjects that (for most of us) fall into that latter category. Over Maron’s head-nodding old-school beat (complete with a hook sampled from Pitch Black’s It’s All Real), Dot drops some knowledge regarding the tough life of an up-and-coming emcee. The legendary Masta Ace takes over on the middle verse, steering the cut into some seriously nostalgic territory: “You don’t know about spitting a battle rap, punk, while your man bangs a beat on a Cadillac trunk / You don’t know about the Union Square in ‘86, I swear it was like a thug reunion there.” If you’re digging this retro-yet-fresh track, you’re sure to find more to your liking on M-Dot’s Run MPC LP, due out August 31.