Exported content is not 'raw'

Exported content is processed through various Drupal filters, which is undesirable, since we want the raw content.

To reproduce:

Save a book page with input format 'Filtered HTML', and make sure that the line break filter is enabled for the Filtered HTML format.

Expected output: the exported node should contain the contents of the node as typed in by the author.

Actual output: the exported node contains extra <br/> elements inserted by the line break filter.