Concerning the bidding system (see pg. 58):
The bid IPC that any player collects from the bank can be used as described on pg. 58.
Exception:
Any units that can only be produced in a Capital (such as Mines, Paratrooper unit, Waffen-SS unit etc.) must be still be produced in a Capital.
Example:
The Allies collect 8 bid IPC from the bank. The Allies players decide that the Soviet Union gets these 8 IPC.
The Soviet player purchases 8 Mines - and must then place them in Moscow (Russia).