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It is possible to specify both a <RawData> document, and
fields such as <Title>, <Description>, etc. The binary
document will be processed, and any other fields provided will
override the values that came from the document.
This can be useful in situations where you have a Content Management System (CMS) that contains metadata about a document that doesn't actually occur anywhere in the document. You can do a custom dataload that pushes in the document, and the custom Title/Description/etc.