If all options are exercised, the deal would be worth $5 billion.
The companies even got a tax break when the options were exercised to buy stock.
The option can be exercised during a 30-day period at the end of the second year.
In many cases, the option can be exercised every five years.
The order could be worth about $1 billion if the options are exercised.
If the options are exercised, the order will be worth $6 billion.
But he added it was not clear when or how the option would be exercised.
If all options are exercised, the value of the contract would be about $256 million.
If options are exercised, work may continue through October 2011.
The contract's value could reach $450 million if all options are exercised.