A limit order names the worst price its owner will accept: a maximum for purchases, a minimum for sales. In options markets, where quotes are wide and negotiated, limit orders are the standard instrument; a market order in a thin option accepts whatever the quote happens to be.
For multi-leg structures the limit applies to the package's net price, which is the number that defines the trade's economics. The craft of limit pricing, anchoring at the fresh mid, conceding in measured steps, respecting the structure's compensation floor, is the subject of execution quality.