diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA1.java b/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA1.java
index f22d76c7..a3470ebc 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA1.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA1.java
@@ -41,28 +41,6 @@ public class DXExporterFromA1 extends DXExporterFromA3 {
 	private static boolean isValidA1(DataSource dataSource) throws IOException {
 		return getPDFAParserValidationResult(PreflightParserHelper.createPreflightParser (dataSource));
 	}
-	/***
-	 * internal helper function: get namespace for order-x
-	 * @param ver the delivery-x version
-	 * @return the URN of the namespace
-	 */
-	@Override
-  public String getNamespaceForVersion(int ver) {
-		// As of late 2022 the Delivery-X standard is not yet published. See specification:
-		// Die digitale Ablösung des Papier-Lieferscheins, Version 1.1, April 2022
-		// Chapter 7.1 XMP-Erweiterungsschema für PDF/A-3
-		// http://docplayer.org/230301085-Der-digitale-lieferschein-dls.html
-		return "urn:factur-x:pdfa:CrossIndustryDocument:despatchadvice:1p0#";
-	}
-	/***
-	 * internal helper: returns the namespace prefix for the given order-x version number
-	 * @param ver the ox version
-	 * @return the namespace prefix as string, without colon
-	 */
-	@Override
-  public String getPrefixForVersion(int ver) {
-		return "fx";
-	}
 
 	private static boolean getPDFAParserValidationResult(PreflightParser parser) throws IOException {
 		/*
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA3.java b/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA3.java
index 3324e36c..006b5c7e 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA3.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/DXExporterFromA3.java
@@ -129,6 +129,29 @@ public class DXExporterFromA3 extends ZUGFeRDExporterFromA3 {
 
 	private boolean attachZUGFeRDHeaders = true;
 
+	/***
+	 * internal helper function: get namespace for order-x
+	 * @param ver the delivery-x version
+	 * @return the URN of the namespace
+	 */
+	@Override
+	public String getNamespaceForVersion(int ver) {
+		// As of late 2022 the Delivery-X standard is not yet published. See specification:
+		// Die digitale Ablösung des Papier-Lieferscheins, Version 1.1, April 2022
+		// Chapter 7.1 XMP-Erweiterungsschema für PDF/A-3
+		// http://docplayer.org/230301085-Der-digitale-lieferschein-dls.html
+		return "urn:factur-x:pdfa:CrossIndustryDocument:despatchadvice:1p0#";
+	}
+	/***
+	 * internal helper: returns the namespace prefix for the given order-x version number
+	 * @param ver the ox version
+	 * @return the namespace prefix as string, without colon
+	 */
+	@Override
+	public String getPrefixForVersion(int ver) {
+		return "fx";
+	}
+
 	/**
 	 * Makes A PDF/A3a-compliant document from a PDF-A1 compliant document (on the
 	 * metadata level, this will not e.g. convert graphics to JPG-2000)
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA1.java b/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA1.java
index 33f95aea..6b4b7e6c 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA1.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA1.java
@@ -41,24 +41,6 @@ public class OXExporterFromA1 extends OXExporterFromA3 {
 	private static boolean isValidA1(DataSource dataSource) throws IOException {
 		return getPDFAParserValidationResult(PreflightParserHelper.createPreflightParser(dataSource));
 	}
-	/***
-	 * internal helper function: get namespace for order-x
-	 * @param ver the order-x version
-	 * @return the URN of the namespace
-	 */
-	@Override
-  public String getNamespaceForVersion(int ver) {
-		return "urn:factur-x:pdfa:CrossIndustryDocument:1p0#";
-	}
-	/***
-	 * internal helper: returns the namespace prefix for the given order-x version number
-	 * @param ver the ox version
-	 * @return the namespace prefix as string, without colon
-	 */
-	@Override
-  public String getPrefixForVersion(int ver) {
-		return "fx";
-	}
 
 	private static boolean getPDFAParserValidationResult(PreflightParser parser) throws IOException {
 		/*
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA3.java b/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA3.java
index 5db1a693..40e181b1 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA3.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/OXExporterFromA3.java
@@ -129,6 +129,25 @@ public class OXExporterFromA3 extends ZUGFeRDExporterFromA3 {
 
 	private boolean attachZUGFeRDHeaders = true;
 
+	/***
+	 * internal helper function: get namespace for order-x
+	 * @param ver the order-x version
+	 * @return the URN of the namespace
+	 */
+	@Override
+	public String getNamespaceForVersion(int ver) {
+		return "urn:factur-x:pdfa:CrossIndustryDocument:1p0#";
+	}
+	/***
+	 * internal helper: returns the namespace prefix for the given order-x version number
+	 * @param ver the ox version
+	 * @return the namespace prefix as string, without colon
+	 */
+	@Override
+	public String getPrefixForVersion(int ver) {
+		return "fx";
+	}
+
 	/**
 	 * Makes A PDF/A3a-compliant document from a PDF-A1 compliant document (on the
 	 * metadata level, this will not e.g. convert graphics to JPG-2000)