The character or characters used to denote hierarchy.
In order to flatten out hierarchical structures, the driver needs some specifier that states the path to a column through the hierarchy. If this value is "." and a column comes back with the name address.city, this indicates that there is a mapped attribute with a child called city. If your data has columns that already use a single period within the attribute name, set the SeparatorCharacter to a different character or characters.