I have read in the archive that to add my own collator to Oxygen, I must drop the jar file in the oxygen lib folder. I have done this, and still get the same error message: F [Saxon-B 9.0.0.6] Collation http://saxon.sf.net/collation?class=CzechCollation has not been defined. The line from my XSLT file is: <xsl:sort select="Author" collation="http://saxon.sf.net/collation?class=CzechCollation"/> The jar tf command tell me the jar file contains the following manifest (I know very little about java): META-INF META-INF/MANIFEST.MF CzechCollation.class However, when I click on the jar , I get the error message: "failed to load Main-Class manifest attribute from ..." I assume this happens because the jar does not contain an application. Anyway, The CzechCollation.java file follows (Substantially shortened). Thanks, Mark import java.text.ParseException; import java.text.RuleBasedCollator; public class CzechCollation extends RuleBasedCollator { public CzechCollation() throws ParseException { super(traditionalCzechRules); } private static String upperAcuteA = new String("\u00c1"); private static String lowerAcuteA = new String("\u00e1"); private static String upperUmlatA = new String("\u00c4"); Many letter definations removed to keep email short private static String upperHacekZ = new String("\u017d"); private static String lowerHacekZ = new String("\u017e"); private static String traditionalCzechRules = ("< A,a," + upperAcuteA + "," + lowerAcuteA + "," + upperUmlatA + "," + lowerUmlatA + Many parts of the string removed to keep email short "< Z,z <" + upperHacekZ + "," + lowerHacekZ);