onsgmls: "1D6C2" is not a character number in the document character set

[Sam Steingold <sds@podval.org>]

with dtd v 4.4 I get these errors:
onsgmls -s -e -g -c/usr/share/sgml/xml.soc clisp.xml
In entity refentry included from clisp.xml:19:0
In entity dbcent included from /usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/docbookx.dtd:123:8
In entity ISOgrk4 included from /usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/dbcentx.mod:360:9
onsgmls:/usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/ent/isogrk4.ent:42:30:E: "1D6C2" is not a character number in the document character set
In entity refentry included from clisp.xml:19:0
In entity dbcent included from /usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/docbookx.dtd:123:8
In entity ISOgrk4 included from /usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/dbcentx.mod:360:9
onsgmls:/usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/ent/isogrk4.ent:43:30:E: "1D6C3" is not a character number in the document character set
In entity refentry included from clisp.xml:19:0
In entity dbcent included from /usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/docbookx.dtd:123:8
In entity ISOgrk4 included from /usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/dbcentx.mod:360:9
onsgmls:/usr/share/sgml/docbook/xml-dtd-4.4-1.0-30/ent/isogrk4.ent:44:30:E: "1D6D8" is not a character number in the document character set

etc

I did not get these errors with 4.3.
what do they mean?
how do I avoid them?
thanks.

-- 
Sam Steingold (http://www.podval.org/~sds) on Fedora Core release 5 (Bordeaux)
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