some peeps bid up, most bid down.
A: 12
B: 11
A: 10
B: ok you get it, I get axis and you get allies at 10.
Going up
A: 8
B: OK, I take it at 8.
The difference with going up is you bid for what the other person will get as the allies. When you go down it is for what you want to take the allies with.