[xslt] xsltproc and entities

["Robert Collins" <robert collins itdomain com au>]

I'm seeing something strange:

I have a docbook xml file with a number of declared entities at the top.
(ie
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"../docbook/xml/docbookx.dtd" [
<!ENTITY general SYSTEM "general.xml">
<!ENTITY license-ptc SYSTEM "licptc.xml">
...

I get the following:
XRef to nonexistent id: q-editors
Error: no ID for constraint linkend: q-contrib-diff.
XRef to nonexistent id: q-contrib-diff
Error: no ID for constraint linkend: q-winzip.
XRef to nonexistent id: q-winzip
Error: no ID for constraint linkend: q-error-font-eof.
XRef to nonexistent id: q-error-font-eof
Error: no ID for constraint linkend: q-winzip.
XRef to nonexistent id: q-winzip
Error: no ID for constraint linkend: gloss-xdmcp.
Error: no ID for constraint linkend: gloss-vpn.
Error: no ID for constraint linkend: gloss-firewall.
...

most of which go away when I replace the entity references with the
content from the referenced files.  this only occurs with xsltproc

Any hints as to where I should look to find a cause?

Rob