3. If neither the filter nor the comparator are specified, the enumeration will traverse all records in the record store in an undefined order.
如果既没有指定过滤器又没有指定比较器，枚举将以未定义的顺序遍历记录存储中的所有记录。
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4. The state of a record updated by two users at the same time is undefined unless the system can guarantee that two users cannot update a record simultaneously.
由两个用户同时更新的记录的状态是未定义的，除非系统可以保证两个用户无法同时更新记录。
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5. The state of a record updated by two users at the same time is undefined unless the system can guarantee that two users cannot update a record simultaneously.
