Good Morning, me again, sorry, the Learn/Do guy, Worked thru building alt configurations after Mr. Pavalkis help, (invaluable) and now have hit a snag, I have provided a screen shot, but can share full md.zip if required, its all fictional. I created a Parametric to compute Muzzle_V based on a division of two masses, the Parametric seems to work correctly (the result of 4 in the screenshot is expected value), even when I select alt configurations in the Variables window, what I spent the night trying to do, unsuccessfully was "tie" the value from that calculation to a requirement ("shall not exceed 3.5" . I feel like I've tried, to the extent of my skill level, and am begging. This really is a last big piece in being able to successfully build a real world model against actual requirements. Thank you V/R Joe