Each action can have an associated link, which, if present, will be displayed as a chain in the link column of the action table view.
You can associate a link to the current action within the link section of the action inspector.
There are three supported types of links:
Moreover you can associate a link by dropping a file from the Finder, a URL from a web browser or a message from Apple Mail on the action itself.
When a link is associated with an action you can open it by double clicking on the chain icon displayed in the link column of the action table view or by selecting the Action > Open Link menu option.