Greg ART stands for Advanced Reticle Technology and all his reticles are opart of that group. Hey look down a couple headings here to the "Videos threads", and i think Ernie has it in his youtubes there. The title i think is called "My favorite Reticle and Dope". The reticle is gonna look a bit different shortly--i think it's gonna have .2 MOA stadia lines probably at the edge of each quadrant for very fine reticle rangefinding apps. like the TMR.
BTW, HUMR stands for Holland's Ultimate Mil Reticle.