diff --git a/Mustang-CLI/pom.xml b/Mustang-CLI/pom.xml
index 4d60dc86..3da16639 100644
--- a/Mustang-CLI/pom.xml
+++ b/Mustang-CLI/pom.xml
@@ -10,7 +10,7 @@
    <artifactId>Mustang-CLI</artifactId>
    <name>Mustang commandline tool</name>
    <packaging>jar</packaging>
-   <version>1.9.0-alpha1</version>
+   <version>1.9.0-alpha1-SNAPSHOT</version>
    <repositories>
       <repository>
          <!-- for jargs -->
@@ -31,7 +31,7 @@
       <dependency>
          <groupId>org.mustangproject</groupId>
          <artifactId>validator</artifactId>
-         <version>2.0.0-SNAPSHOT</version>
+         <version>1.9.0-alpha1</version>
          <!-- prototypes of new mustangproject versions can be installed by referring to them and installed to the local repo from a jar file with
         mvn install:install-file -Dfile=mustang-1.5.4-SNAPSHOT.jar -DgroupId=org.mustangproject.ZUGFeRD -DartifactId=mustang -Dversion=1.5.4 -Dpackaging=jar -DgeneratePom=true
         -->
diff --git a/library/pom.xml b/library/pom.xml
index 0c082a08..0dab7a26 100644
--- a/library/pom.xml
+++ b/library/pom.xml
@@ -9,7 +9,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.mustangproject</groupId>
 	<artifactId>library</artifactId>
-	<version>1.9.0-alpha1</version>
+	<version>1.9.0-alpha1-SNAPSHOT</version>
 	<packaging>jar</packaging>
 	<name>Library to write and read FacturX and ZUGFeRD e-invoices.  </name>
 	<description>The Mustang project is a java library to read and write ZUGFeRD meta data inside your invoice PDFs. To write files, a provided PDF/A will be combined with generated or provided XML.
diff --git a/validator/pom.xml b/validator/pom.xml
index 2746d7c1..b7fdca77 100644
--- a/validator/pom.xml
+++ b/validator/pom.xml
@@ -12,7 +12,7 @@
     <name>Library to validate Factur-X/ZUGFeRD 1.0 and 2.1 as well as XRechnung e-invoices.</name>
 
     <packaging>jar</packaging>
-    <version>1.9.0-alpha1</version>
+    <version>1.9.0-alpha1-SNAPSHOT</version>
     <repositories>
         <repository>
             <!-- for jargs -->
diff --git a/validator/src/main/java/org/mustangproject/validator/Validator.java b/validator/src/main/java/org/mustangproject/validator/Validator.java
index bc776a4c..c1986a55 100644
--- a/validator/src/main/java/org/mustangproject/validator/Validator.java
+++ b/validator/src/main/java/org/mustangproject/validator/Validator.java
@@ -25,20 +25,37 @@ public abstract class Validator {
 	}
 	
 	//abstract method
-	
+
+	/***
+	 * prepare validation
+	 * @param filename the filename of the xml file to be examined
+	 * @throws IrrecoverableValidationError when any fatal errors arise, e.g. when the source file can not be found
+	 */
 	public abstract void setFilename(String filename) throws IrrecoverableValidationError;
+
+	/***
+	 * perform the validation
+	 * @throws IrrecoverableValidationError any fatal errors, e.g. when the source file can not be found
+	 */
 	public abstract void validate() throws IrrecoverableValidationError;
 
+	/**
+	 * get validation result
+	 * @return validation result as xml string
+	 */
 	public String getXMLResult() {
 		return context.getXMLResult();
 	}
 	
 	/***
 	 * validates a schema, which can only be needed in XML validation - and in pdf validation for additional data
-	 * @param xmlRawData
-	 * @param schemaPath
+	 * @param xmlRawData the XML to be validated
+	 * @param schemaPath the filename of the schema file
+	 * @param section the error message type code
+	 * @param part whether the error message occurs in the pdf or xml part
+	 * @throws IrrecoverableValidationError when any fatal errors arise, e.g. when the source file can not be found
 	 */
-	protected void validateSchema(byte[] xmlRawData, String schemaPath,int section, EPart part) throws IrrecoverableValidationError {
+	protected void validateSchema(byte[] xmlRawData, String schemaPath, int section, EPart part) throws IrrecoverableValidationError {
 		URL schemaFile = ClassLoader.getSystemResource("schema/" + schemaPath);
 		Source xmlData = new StreamSource(new ByteArrayInputStream(xmlRawData));
 		SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
diff --git a/validator/src/main/java/org/mustangproject/validator/XMLValidator.java b/validator/src/main/java/org/mustangproject/validator/XMLValidator.java
index c40c881b..8b804425 100644
--- a/validator/src/main/java/org/mustangproject/validator/XMLValidator.java
+++ b/validator/src/main/java/org/mustangproject/validator/XMLValidator.java
@@ -51,6 +51,11 @@ public class XMLValidator extends Validator {
 		super(ctx);
 	}
 
+	/***
+	 * set source file
+	 * @param name
+	 * @throws IrrecoverableValidationError
+	 */
 	public void setFilename(String name) throws IrrecoverableValidationError { // from XML Filename
 		filename = name;
 		// file existence must have been checked before
@@ -69,10 +74,20 @@ public class XMLValidator extends Validator {
 		}
 	}
 
+	/***
+	 * manually set the xml content
+	 * @param xml the xml to be checked
+	 */
 	public void setStringContent(String xml) {
 		zfXML = xml;
 	}
 
+	/**
+	 * whether uri1 has the same meaning like uri1 (it has, if it only differs in the fragment, i.e. uri1#1==uri1#2 )
+	 * @param uri1
+	 * @param uri2
+	 * @return true if semantically identical
+	 */
 	public static boolean matchesURI(String uri1, String uri2) {
 		return (uri1.equals(uri2) || uri1.startsWith(uri2 + "#"));
 	}
@@ -85,13 +100,10 @@ public class XMLValidator extends Validator {
 		disableNotices = true;
 	}
 
+
 	/***
-	 *
-	 * @param xmlString
-	 * @param overrideProfileCheck
-	 *            if set to true, all ZF2 files will be checked against EN16931
-	 *            schematron, since no other schematron is available
-	 * @return
+	 * perform validation
+	 * @throws IrrecoverableValidationError if any fatal errors occur, e.g. source file can not be read
 	 */
 	@Override
 	public void validate() throws IrrecoverableValidationError {
@@ -315,6 +327,14 @@ public class XMLValidator extends Validator {
 	}
 
 
+	/***
+	 * validate using a xslt file generated from a schematron in the build preparation of this software
+	 * @param xml the xml to be checked
+	 * @param xsltFilename the filename of the intermediate XSLT file
+	 * @param section the error type code, if one arises
+	 * @param severity how serious a error should be treated - may only be notice
+	 * @throws IrrecoverableValidationError if anything happened that prevents further checks
+	 */
 	public void validateSchematron(String xml, String xsltFilename, int section, ESeverity severity) throws IrrecoverableValidationError {
 		ISchematronResource aResSCH = null;
 		aResSCH = SchematronResourceXSLT.fromClassPath(xsltFilename);