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You can toggle public links, comments, internal comments, attachments, public attachments, linked issues, sub-tasks, issue transition, worklog and changelog.
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Defaults tab
You can select the state at which each of the options must be in when a new share is created, please note that the default tab does not enforce the estate of these options but simply pre-selects them for your convenience.
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Security tab
You can enforce security policies for new and updated shares, define link expiration dates, and require a password to view the link.
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