Each merge field in a WordWriter template must bind to a data source field/value pair. The number of merge fields in the main template document (the part of the document that is not within a repeat block) may not exceed the number of values in the data source defined by SetDataSource. However, the number of values in the data source may be greater than the number of merge fields in the main template document.
Do not call this method more than once for a single instance of WordTemplate. To set multiple main document data sources, use the following methods:
SetDataSource(Object(), String(), String)