So, I'm a bit confused about a capped ranges.

Let's say that MP raises first in, HJ and CO fold, BTN calls and both blinds fold, so it's HU.

We'll say that the flop is J-7-4 rainbow. MP checks and the BTN checks behind.

Because MP has declined to Cbet, are we considering MP to be capped, with what is probably a weak hand that isn't good enough to bet a J-7-4 combo, or does he remain uncapped, because he didn't Cbet? What if MP had a hand like AA77 and checked? Is he still considered capped, even though his hand is very strong?

Since MP doesn't Cbet and the BTN checks behind, I assume the button remains uncapped?

Moving forward, let's say that an offsuit 3 hits the turn, giving us a full rainbow board. At this point, if MP bets, is he considered to be capped or is it a delayed Cbet or both?

In general, IP caps his range by checking back board x, while OOP should still have very strong hands in his range so he remains uncapped.

In your example, both players can still have 56 with that flop action so they are not capped. Is it a delayed cbet? At least the way I define a delayed cbet it clearly is.