A short phrase or label for each schedule activity used in conjunction with an activity identifier to differentiate that project schedule activity from other schedule activities.

活动描述是一个短语或标签，与活动编码一起，用来区分不同的项目活动。

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Apple has also added a way to reset your Advertising Identifier, which acts as a control room for informing advertisers about your web activity.

CNN: Apple rolls out iOS 6.1 update