The task also has a start node, however, this node is optional and does not change the execution semantics of the task, which can only begin execution when the input is available.

该任务也有一个开始节点，不过，这个节点是可选的，不会改变任务的执行语义，这个任务只有在该输入可用的情况下才会开始执行。

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Change to the cardinality of fields in the output message, such as changing mandatory fields to optional fields, will break existing consumers.

对输出消息中的字段的基数性进行更改(如将强制字段更改为了可选字段)将中断现有使用者。

youdao

The first basic change presented in Listing 4 is the extension of the ACORD schema by adding an optional element for a party's social security number (SSN).

清单4中的第一种基本变化是ACORD模式的扩展，增加了一个可选元素表示参与者的社会安全号码(SSN)。

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