I was bit by this bug today. I was trying to use <code> inside a <para>, which has been there since DocBook 4.3.
The most current DocBook XML release, is 4.5: http://www.docbook.org/schemas/4x A RNG version of the DocBook 4.5 schema can be picked up from the above URL. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]

