All the data stored in InfoPath forms are stored in an XML format, which is referred to as the "data source". The form template must have one primary data source for submitting data and can have multiple secondary data sources for retrieving data into the form.
In InfoPath forms, all stored data is formatted as XML and designated as the "data source". Each form template should contain a single primary data source for submitting information and may have additional secondary data sources to retrieve further details.