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Clicking the little downward arrow next to the Identity selection, a field opens up with a details panel that consists of the three subtitles. These are "Type", "Begins at" and "Expires at".
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Type: consists of the two options for managing identity's permission. Those are allow and deny.
Begins At (optional): start date of a permission period. If type of allow you can access that folder after begins date. If type of deny, you can't access that folder after begins date.
Expires At (optional): end date of a permission period. If type of allow you can't access that folder after expires date. If type of deny, you can access that folder after expires date.
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