However, this WSDL file, or the contract, does not declare which element (s) may be a required or optional variable for the invocation.
然而，WSDL文件，或者说协议并没有指明哪一个元素是调用服务必须的或可选的变量。
2
Optional ships will be considered part of same series of sister vessels if the option is exercised not later than 1 year after the contract to build the series was signed.
选择权船舶将被认为属于系列姐妹船的一部分，条件是其选择权在系列船舶合同签署之后1年之内生效。
3
Optional ships will be considered part of same series of vessels if the option is exercised not later than 1 year after the contract to build the series was signed.