DOCBOOK: No attribute value 'PDF' in imagedata

[Joachim Ziegler]

Hello,

I've just tried the following from Bob Staytons 2using the XSLT 
Stylesheets":

Example 16.1. Multiple graphics in a mediaobject

<mediaobject  id="MousePicture">
  <imageobject  role="html">
    <imagedata  format="PNG"  fileref="mouse.png"/>
  </imageobject>
  <imageobject  role="fo">
    <imagedata  format="PDF"  fileref="mouse.pdf"/>
  </imageobject>
</mediaobject>


But xmllint says:

 validity error: Value "PDF" for attribute format of imagedata is not 
among the enumerated set

and nsgmls says:

value of attribute "format" cannot be "PDF"; must be one of "BMP", 
"CGM-CHAR", "CGM-BINARY", "CGM-CLEAR", "DITROFF", "DVI", "EPS", "EQN", 
"FAX", "GIF", "GIF87a", "GIF89a", "JPG", "JPEG", "IGES", "PCX", "PIC", 
"PNG", "PS", "SGML", "TBL", "TEX", "TIFF", "WMF", "WPG", "SVG", 
"linespecific"

I am using

 PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

So what is the preferred way of including scalable vector graphics for 
PDF output?

Greetings,
Joachim