diff --git a/validator/src/main/java/org/mustangproject/validator/XMLValidator.java b/validator/src/main/java/org/mustangproject/validator/XMLValidator.java
index e20879e0..22a3aaac 100644
--- a/validator/src/main/java/org/mustangproject/validator/XMLValidator.java
+++ b/validator/src/main/java/org/mustangproject/validator/XMLValidator.java
@@ -51,7 +51,7 @@ public class XMLValidator extends Validator {
 
 	/***
 	 * set source file
-	 * @param name
+	 * @param name the absolute filename of an xml file to validate
 	 * @throws IrrecoverableValidationError
 	 */
 	public void setFilename(String name) throws IrrecoverableValidationError { // from XML Filename
@@ -82,8 +82,8 @@ public class XMLValidator extends Validator {
 
 	/**
 	 * 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
+	 * @param uri1 basis guideline ID
+	 * @param uri2 guideline ID to be checked
 	 * @return true if semantically identical
 	 */
 	public static boolean matchesURI(String uri1, String uri2) {
diff --git a/validator/src/main/java/org/mustangproject/validator/ZUGFeRDValidator.java b/validator/src/main/java/org/mustangproject/validator/ZUGFeRDValidator.java
index 6b1b166c..1e413e63 100644
--- a/validator/src/main/java/org/mustangproject/validator/ZUGFeRDValidator.java
+++ b/validator/src/main/java/org/mustangproject/validator/ZUGFeRDValidator.java
@@ -46,6 +46,7 @@ public class ZUGFeRDValidator {
 	 * within the validation it turned out something in the options was wrong, e.g.
 	 * the file did not exist. recommendation to show the help text again. Should be
 	 * false if XML or PDF file was found
+	 * @return false if any valid option was picked up
 	 */
 	public boolean hasOptionsError() {
 		return !optionsRecognized;
@@ -59,7 +60,7 @@ public class ZUGFeRDValidator {
 	/***
 	 * in case the result was not valid the error code of the app will be set to -1
 	 * 
-	 * @return
+	 * @return true if both xml and pdf were valid (contained no errors, notices are ignored)
 	 */
 	public boolean wasCompletelyValid() {
 		return wasCompletelyValid;
@@ -69,8 +70,8 @@ public class ZUGFeRDValidator {
 	/***
 	 * performs a validation on the file filename
 	 * 
-	 * @param filename
-	 * @return
+	 * @param filename the complete absolute filename of a PDF or XML
+	 * @return a xml string with the validation result
 	 */
 	public String validate(String filename) {
 		boolean xmlValidity;