API reference for Subscriptions 6
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This module enables users to subscribe to be notified of changes to nodes or taxonomies, such as new comments in specific forums, or additions to some category of blog. Once enabled, all nodes will have an additional link that allows the user to change their subscriptions. Users get a tab on their user page to manage their own subscriptions. Users can also set an auto-subscribe function which notifies the user if anyone comments on posts they have made. Admins can turn this on by default.