Closes #45

src/main/java/org/mustangproject/ZUGFeRD/ZUGFeRD1PullProvider.java

@@ -9,6 +9,7 @@ import javax.xml.bind.JAXBException;
 import javax.xml.bind.Marshaller;
 
 import org.mustangproject.ZUGFeRD.model.CrossIndustryDocumentType;
+import org.mustangproject.ZUGFeRD.model.ZFNamespacePrefixMapper;
 
 public class ZUGFeRD1PullProvider implements IXMLProvider {
 	
@@ -33,6 +34,7 @@ public class ZUGFeRD1PullProvider implements IXMLProvider {
 			marshaller = JAXBContext.newInstance("org.mustangproject.ZUGFeRD.model").createMarshaller();
 			marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
 			marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
+			marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", new ZFNamespacePrefixMapper());
         } catch (JAXBException e) {
             throw new ZUGFeRDExportException("Could not initialize JAXB", e);
         }

src/main/java/org/mustangproject/ZUGFeRD/model/ZFNamespacePrefixMapper.java

@@ -0,0 +1,31 @@
+package org.mustangproject.ZUGFeRD.model;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.sun.xml.bind.marshaller.NamespacePrefixMapper;
+
+public class ZFNamespacePrefixMapper extends NamespacePrefixMapper {
+
+	private Map<String, String> namespaceMap = new HashMap<>();
+ 
+	/**
+	 * Create mappings.
+	 */
+	public ZFNamespacePrefixMapper() {
+
+		namespaceMap.put("urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:12", "ram");
+		namespaceMap.put("urn:un:unece:uncefact:data:standard:UnqualifiedDataType:15", "udt");
+		namespaceMap.put("urn:ferd:CrossIndustryDocument:invoice:1p0", "rsm");
+	}
+ 
+	/* (non-Javadoc)
+	 * Returning null when not found based on spec.
+	 * @see com.sun.xml.bind.marshaller.NamespacePrefixMapper#getPreferredPrefix(java.lang.String, java.lang.String, boolean)
+	 */
+	@Override
+	public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
+		return namespaceMap.getOrDefault(namespaceUri, suggestion);
+	}
+
+}