Can I include unstructured files in the general rule for a book ?

Hi,

I have a series of books with lots of generated files. I want to keep those as they are, but still add structure to the book and the content chapters. How do I write a general rule for the book element that allows an unstructured component - i.e. without wrapping the unstructured content into a container first (which would involve structuring the generated files with a special conversion table just to set the root element for them). Is this possible at all ?

Thanks

Jang