DOCBOOK: Validation Error with article XML Document in Chinese

[Sidney Lu <lu@sinica.edu.tw>]

Title:

I wrote an article with docbook DTD in Chinese, but failed to validate with
the following error messages:

...
cd /home/lu/Documents/
nsgmls -s  EditArticleWithEmacs.xml
nsgmls:EditArticleWithEmacs.xml:5:13:E: non SGML character number 152
nsgmls:EditArticleWithEmacs.xml:5:16:E: non SGML character number 152
nsgmls:EditArticleWithEmacs.xml:5:24:E: non SGML character number 152
nsgmls:EditArticleWithEmacs.xml:5:27:E: non SGML character number 152
nsgmls:EditArticleWithEmacs.xml:5:33:E: non SGML character number 152
nsgmls:EditArticleWithEmacs.xml:5:36:E: non SGML character number 152
nsgmls:EditArticleWithEmacs.xml:8:17:E: non SGML character number 152
...

I use Emacs with psgml mode.

I also edited an slides document with slides.dtd designed by Norman Walsh.
Some Chinese text were in the slides.xml document and it validated fine.
I am wondering why these two documents behaviored differently.  The command
used to validate is 'nsgmls -s myxml.xml', and /usr/share/sgml/xml.dcl is
declared as an SGMLDECL entry in /etc/sgml/catalog file.

Any help is much appreciated.

Followed are these two xml fragments:

slides.xml
========
<?xml version="1.0" encoding="big5"?>
<!DOCTYPE slides PUBLIC "-//Norman Walsh//DTD Slides XML V1.1//EN" "slides.dtd">
<slides>
    <slidesinfo>
        <title>CHINESE TEXT HERE
</title>
        <author>
            <honorific>Dr</honorific>
            <firstname/>
            <othername>CHINESE TEXT HERE
</othername>
            <surname>CHINESE SURNAME HERE
</surname>
            <affiliation>
                <jobtitle>Director</jobtitle>
                <orgname>Computing Centre, Academia Sinica</orgname>
            </affiliation>
        </author>
        <mediaobject>
...


EditArticleWithEmacs.xml
=========

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
<article>
  <articleinfo>
      <title>CHINESE TEXT HERE
</title>
    <author>
      <!-- one of (CONTRIB AUTHORBLURB AFFILIATION OTHERNAME LINEAGE SURNAME
FIRSTNAME HONORIFIC) -->
      <honorific>CHINESE TEXT HERE
</honorific>
      <firstname>CHINESE FIRSTNAME
</firstname>
      <surname>CHINESE SURNAME
</surname>
    </author>
  </articleinfo>
  <para>EmacsSGML, SGMLXML,
  <ulink url="http://www.oasis-open.org/">OASIS</ulink>(Organization
  for the Advancement of Structured Information Standards)
  DocBookSGML/XML.
  Emacs SGML/XML, 
  DocBook(article), XMLHTML.
  </para>
</article>