An External History Rule fulfills the same role as a local history rule, except for the fact that the messages to which it relates are provided by another advanced smart asset. As such, it exposes as single additional property:
•Advanced Smart Asset: selection of an advanced smart asset from which to source messages is mandatory. The current asset cannot be chosen. You can populate the property using browse or drag and drop. Having selected an advanced smart asset, standard inline and context menu file property features are available at the same. You can also clear your selection.
Other properties are as the Local History Rule.