When you append data to an XML document, use a source-based or user-defined commit in the session. Use a single point in the mapping to generate transactions. All the projected groups of an XML target must belong to the same transaction control unit.
For sessions using source-based commits, the single transaction point might be a source or nearest active source to the XML target, such as the last active transformation before the target. For sessions with user-defined commits, the transaction point is a transaction generating transformation.