UCP600中on or about

UCP600中on or about
请问UCP600中的 on or about 所说的起迄日均包括在内 ,是什么意思?
The expression on or about or similar will be interpreted as a stipulation that an event is to occur during a period of five calendar days before until five calendar days after the specified date, both start and end dates included. 于或约于或类似措辞将被理解为一项约定,按此约定,某项事件将在所述日期前后各五天内发生,起迄日均包括在内 .
例如说 shipmen on or about 15th may”那装运期是什么时候? 15这一天需要算进去吗?
谢谢了

就单从你举例的来看,装运日期应该是10th 到20th,具体的得结合信用证其它条款.
UCP600中还有如下表述,可以借助“before”和“after”的解释来佐证.
The words to, until, till, “from” and “between” when used to determine a period of
shipment include the date or dates mentioned, and the words “before” and after exclude
the date mentioned.