When you approve a document you fill in:

Message to the author (not mandatory - this will show in the e-mail to the author and only there)
How long the document shall be valid for (see picture below) - default value will come up automatically
If you want the system to send an e-mail to the author when the document expires (who will have the mail is set in the Variables)
Significant update: if this is version 2 or more of a document you need to decide if it is a significant update or not. If it is a significant update this means that all users with this document in a role, need to read the document again.
APPROVE

Document valid for - you can select between:

The choice "valid for unlimited" is practical if you add reports and other documentation to the system that shall not be renewed.

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