The act of making the first voluntary bet in a betting round is called opening the round. On the first betting round, it is also called opening the pot, though in variants where blind bets are common, the blind bets "open" and other players call and/or raise the "big blind" bet. Some poker variations have special rules about opening a round that may not apply to other bets. For example, a game may have a betting structure that specifies different allowable amounts for opening than for other bets, or may require a player to hold certain cards to open.