When you add an XML source definition to a mapping, you need to connect the source definition to an XML Source Qualifier transformation. The XML Source Qualifier transformation defines the data elements that the Integration Service reads during a session. The source qualifier determines how the PowerCenter reads the source data. The XML Source Qualifier transformation is an active transformation.
You can manually add a source qualifier transformation, or you can create a source qualifier transformation by default when you add a source definition to a mapping.
You can edit some of the properties and add metadata extensions to an XML Source Qualifier transformation.
When you connect an XML Source Qualifier transformation in a mapping, you must follow rules to create a valid mapping.