Looks like there is an inconsistencies:
--docbook-document-element=<ROOT ELEMENT> -r <ROOT ELEMENT> - The root element of the document. Possible values are: book and article. The default value is article. while: The option "--docbook-document-element" has an invalid value of "boo". Possible values are: article, book, reference. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org