DOCBOOK-APPS: XMetal and inline elements

Hi!

I've noticed some strange behaviour while using XMetal for creating
DocBook content.
According to "DocBook The Definitive Guide" you can insert inline
elements within other
inline elements.

I've a document wich contains somethinf like this

<action>
<phrase arch="print">Folgendes Dialogfenster wird
ge&ouml;ffnet:</phrase>
 <phrase arch="online">Das Dialogfenster f&uuml;r die Textsuche  wird
ge&ouml;ffnet.</phrase>
</action>

XMetal says that this is an invalid document!! We are using Saxon to
convert the
files into HTML and OpenJade to convert them to RTF and everything works

fine. Since XSLT-Engines normally don't validate the documents, I wanted
to
know if this really invalid or is this just a bug of the DTD-Parser of
XMetal

Thanks.

Ali