COMMAND NAME Edit
upgrade - Update the tech of a ship/unit/plane to the current tech level
[##:##] Command : upgrade <l|s|p> <land units|ships|planes>
The upgrade command allows a country to set the tech level of its ships/land units/planes to the country's current tech level.
Each ship/land unit/plane to be upgraded must be at least 60% efficient and be in one of the country's harbors/headquarters/airports that is at least 60% efficient.
Upgrading costs 15% of the full build cost in money and avail, and reduces the efficiency of the ship/land unit/plane by 35%. Repairing these 35% will then consume work and resources as usual.