as bidding is not a part of the official game, bid rules differ upon who is playing.
i have played hundreds of games of triplea live in the lobby and pbem(play by e-mail) in the old triplea ladder ranking, the vast majority of games i have played are revised, some global, and very few anniversary. below is what i have seen.
the most common rules that i have played with(near universal amongst triplea players) is
1. bid ipcs can be used to place units pregame
2. units can only be placed in territories or seazones that already have a unit of the same power
rules that i have seen frequently
1. only one bid unit per territory or seazone
2. bid for the alliance that you think is disadvantaged and bid down. (i prefer to use the method used at conventions of bidding for your opponent to play the disadvantaged alliance and bid up.)
rules i have never played or been asked to use but have seen
1. all bid ipc must be spent in units and not added to any powers starting income
2. no bid units to certain powers(such as china)
