Mind you, this was 4 presidents ago, so I could be mistaken or just remembering a bad GM, but something along the lines of "the action you declared is the only action you can take." Kind of the way readied actions work now. If the trigger never happens, you don't act.
Oh right, I remember those, "Called actions." There was a person at the table (a "caller") who would collect everyone's actions and declare them to the DM at the start of every turn. There's a version of this in the BECM rules, actually. From page 5 of the Rules Cyclopedia:
Mapping and Calling
Although each person will be playing the role of a character, the players should also handle the jobs of mapping and calling. Any player can be the mapper or caller.
The mapper is the player who draws a map of the dungeon as it is explored. One or more of the characters should be making maps, but one of the players must make the actual map. The map should be kept on the table for all to see and refer to. Pencil should be used when making the map, incase of errors or tricky passages.
If the party's movement carries it into new and unmapped territory, the DM will describe the area in detail so the party's mapper can map it. If something such as a secret door or treasure item is discovered, the DM describes it and announces the results if the characters examine it.
The caller is a player selected by the other players to describe party actions so the DM doesn't have to listen to several voices at once. He or she tells the DM what the party is doing this turn. If the DM prefers, each individual can describe his own actions. The caller is just a convenience in many campaigns; it's not a game rule that players have to use.
I cut my teeth on the BECM rules. And honstly? Sometime, it's very helpful to have a caller at the table--especially if you have a group that likes to make decisions by committee, or who like to roll Initiative every turn and then carefully plan everything out. But...well. I've played in games where the DM took the caller
very seriously, and would stick to the actions that the caller declared
no matter what. If an action became impossible due to movement or actions of the monster? Oh well, you should have thought of that, ha ha, sucks to be you, you just lost your turn.
But that was never the intent of having a caller; the rules are pretty explicit that the "job" of being a caller was purely a convenience. But I know at least one DM who would abuse it just to mess with the players.
