diff --git a/addressbook/inc/class.addressbook_groupdav.inc.php b/addressbook/inc/class.addressbook_groupdav.inc.php
index 01b03250ff..39f93fc189 100644
--- a/addressbook/inc/class.addressbook_groupdav.inc.php
+++ b/addressbook/inc/class.addressbook_groupdav.inc.php
@@ -328,6 +328,21 @@ class addressbook_groupdav extends groupdav_handler
 	/**
 	 * Add extra properties for addressbook collections
 	 *
+	 * Example for supported-report-set syntax from Apples Calendarserver:
+	 * <D:supported-report-set>
+	 *    <supported-report>
+	 *       <report>
+	 *          <addressbook-query xmlns='urn:ietf:params:xml:ns:carddav'/>
+	 *       </report>
+	 *    </supported-report>
+	 *    <supported-report>
+	 *       <report>
+	 *          <addressbook-multiget xmlns='urn:ietf:params:xml:ns:carddav'/>
+	 *       </report>
+	 *    </supported-report>
+	 * </D:supported-report-set>
+	 * @link http://www.mail-archive.com/calendarserver-users@lists.macosforge.org/msg01156.html
+	 *    
 	 * @param array $props=array() regular props by the groupdav handler
 	 * @return array
 	 */
@@ -335,8 +350,12 @@ class addressbook_groupdav extends groupdav_handler
 	{
 		// supported reports (required property for CardDAV)
 		$props[] =	HTTP_WebDAV_Server::mkprop('supported-report-set',array(
-			HTTP_WebDAV_Server::mkprop('supported-report','addressbook-query'),
-			HTTP_WebDAV_Server::mkprop('supported-report','addressbook-multiget'),
+			HTTP_WebDAV_Server::mkprop('supported-report',array(
+				HTTP_WebDAV_Server::mkprop('report',
+					HTTP_WebDAV_Server::mkprop(groupdav::CARDDAV,'addressbook-query','')))),
+			HTTP_WebDAV_Server::mkprop('supported-report',array(
+				HTTP_WebDAV_Server::mkprop('report',
+					HTTP_WebDAV_Server::mkprop(groupdav::CARDDAV,'addressbook-multiget','')))),
 		));
 		return $props;
 	}
diff --git a/egw-pear/HTTP/WebDAV/Server.php b/egw-pear/HTTP/WebDAV/Server.php
index e68691c3cf..94dd2170a6 100644
--- a/egw-pear/HTTP/WebDAV/Server.php
+++ b/egw-pear/HTTP/WebDAV/Server.php
@@ -757,44 +757,6 @@ class HTTP_WebDAV_Server
                                 . gmdate("D, d M Y H:i:s ", $prop['val'])
                                 . "GMT</D:getlastmodified>\n";
                             break;
-                        case "resourcetype":
-                        case "supported-report-set":
-                        	if (!is_array($prop['val'])) {
-                            	echo "     <D:$prop[name]><D:$prop[val]/></D:$prop[name]>\n";
-                        	} else {	// multiple resourcetypes from different namespaces as required by GroupDAV
-                       			$vals = $extra_ns = '';
-                        		foreach($prop['val'] as $subprop)
-                        		{
- 		                            if ($subprop['ns'] && $subprop['ns'] != 'DAV:') {
-										// register property namespace if not known yet
-	                            		if (!isset($ns_hash[$subprop['ns']])) {
-			                                $ns_name = "ns".(count($ns_hash) + 1);
-			                                $ns_hash[$subprop['ns']] = $ns_name;
-	                            		} else {
-	                            			$ns_name = $ns_hash[$subprop['ns']];
-	                            		}
-		                            	if (strchr($extra_ns,$extra=' xmlns:'.$ns_name.'="'.$subprop['ns'].'"') === false) {
-			                                $extra_ns .= $extra;
-		                            	}
-		                            	$ns_name .= ':';
-		                            } elseif ($subprop['ns'] == 'DAV:') {
-		                            	$ns_name = 'D:';
-		                            } else {
-		                            	$ns_name = '';
-		                            }
-		                            // check if $prop[val] should be returned as attribute or value
-		                            if ($subprop['name'] == $subprop['val'] || 
-		                                $subprop['name'] == $prop['name']) {
-		                            	$vals .= "<$ns_name$subprop[val]/>";
-		                            } else {
-		                            	$vals .= "<$ns_name$subprop[name]>$subprop[val]</$ns_name$subprop[name]>";
-		                            }
-                        		}
-                        		echo "     <D:$prop[name]$extra_ns>$vals</D:$prop[name]>\n";
-                        		//error_log(array2string($prop));
-                        		//error_log("<D:$prop[name]$extra_ns>$vals</D:$prop[name]>");
-                        	}
-                            break;
                         case "supportedlock":
                             echo "     <D:supportedlock>$prop[val]</D:supportedlock>\n";
                             break;
@@ -804,10 +766,11 @@ class HTTP_WebDAV_Server
                             echo "     </D:lockdiscovery>\n";
                             break;
                         default:
-                        	if (is_array($prop['val'])) error_log($file['path'].': '.$prop['name'].'='.array2string($prop['val']));
-                            echo "     <D:$prop[name]>"
-                                . $this->_prop_encode(htmlspecialchars($prop['val']))
-                                .     "</D:$prop[name]>\n";
+                            echo "     <D:$prop[name]>".
+                            	(is_array($prop['val']) ?
+	                                $this->_hierarchical_prop_encode($prop['val']) : 
+	                                $this->_prop_encode(htmlspecialchars($prop['val']))).
+	                            "</D:$prop[name]>\n";
                             break;
                         }
                     } else {
@@ -2122,6 +2085,45 @@ class HTTP_WebDAV_Server
         return urldecode($path);
     }
 
+    /**
+     * Encode a hierarchical properties like:
+     * 
+ 	 * <D:supported-report-set>
+	 *    <supported-report>
+	 *       <report>
+	 *          <addressbook-query xmlns='urn:ietf:params:xml:ns:carddav'/>
+	 *       </report>
+	 *    </supported-report>
+	 *    <supported-report>
+	 *       <report>
+	 *          <addressbook-multiget xmlns='urn:ietf:params:xml:ns:carddav'/>
+	 *       </report>
+	 *    </supported-report>
+	 * </D:supported-report-set>
+     * 
+     * @param array $props
+     * @return string
+     */
+	function _hierarchical_prop_encode(array $props)
+    {
+    	//error_log(__METHOD__.'('.array2string($props).')');
+    	if (isset($props['name'])) $props = array($props);
+    	
+    	$ret = '';
+    	foreach($props as $prop)
+    	{
+	    	$ret .= '<'.$prop['name'].
+	    		($prop['ns'] != 'DAV:' ? ' xmlns="'.$prop['ns'].'"' : '').
+	    		(empty($prop['val']) ? ' />' : '>'.
+	    			(is_array($prop['val']) ? 
+	    				$this->_hierarchical_prop_encode($prop['val']) :
+	    				$this->_prop_encode($prop['val'])).
+	    			'</'.$prop['name'].'>');
+    	}
+    	//error_log(__METHOD__.'('.array2string($props).') = '.array2string($ret));
+    	return $ret;
+    }
+
     /**
      * UTF-8 encode property values if not already done so
      *
diff --git a/phpgwapi/inc/class.groupdav.inc.php b/phpgwapi/inc/class.groupdav.inc.php
index ddc2044b1f..f4fa71d256 100644
--- a/phpgwapi/inc/class.groupdav.inc.php
+++ b/phpgwapi/inc/class.groupdav.inc.php
@@ -275,13 +275,13 @@ class groupdav extends HTTP_WebDAV_Server
 			if ($prop == 'resourcetype')
 			{
 				$resourcetype = array(
-					self::mkprop('collection','collection'),
+					self::mkprop('collection',''),
 				);
 				if (!$no_extra_types)
 				{
 					foreach($this->root[$app]['resourcetype'] as $ns => $type)
 					{
-						$resourcetype[] = self::mkprop($ns,'resourcetype', $type);
+						$resourcetype[] = self::mkprop($ns,$type,'');
 					}
 				}
 				$props[] = self::mkprop('resourcetype',$resourcetype);
@@ -389,7 +389,7 @@ class groupdav extends HTTP_WebDAV_Server
 		{
 			if (!isset($collection_props))
 			{
-				$collection_props = self::props2array($file['props']);
+				$collection_props = $this->props2array($file['props']);
 				echo '<h3>'.lang('Collection listing').': '.htmlspecialchars($collection_props['DAV:displayname'])."</h3>\n";
 				continue;	// own entry --> displaying properies later
 			}
@@ -398,7 +398,7 @@ class groupdav extends HTTP_WebDAV_Server
 				echo "<table>\n\t<tr class='th'><th>#</th><th>".lang('Name')."</th><th>".lang('Size')."</th><th>".lang('Last modified')."</th><th>".
 					lang('ETag')."</th><th>".lang('Content type')."</th><th>".lang('Resource type')."</th></tr>\n";
 			}
-			$props = self::props2array($file['props']);
+			$props = $this->props2array($file['props']);
 			//echo $file['path']; _debug_array($props);
 			$class = $class == 'row_on' ? 'row_off' : 'row_on';
 			if (substr($file['path'],-1) == '/')
@@ -448,13 +448,13 @@ class groupdav extends HTTP_WebDAV_Server
 	 * @param mixed $value
 	 * @return string
 	 */
-	protected static function prop_value($value)
+	protected function prop_value($value)
 	{
 		if (is_array($value))
 		{
 			if (isset($value[0]['ns']))
 			{
-				$value = self::props2array($value);
+				$value = $this->_hierarchical_prop_encode($value);
 			}
 			$value = htmlspecialchars(array2string($value));
 		}
@@ -475,7 +475,7 @@ class groupdav extends HTTP_WebDAV_Server
 	 * @param array $props
 	 * @return array
 	 */
-	protected static function props2array(array $props)
+	protected function props2array(array $props)
 	{
 		$arr = array();
 		foreach($props as $prop)
@@ -497,16 +497,8 @@ class groupdav extends HTTP_WebDAV_Server
 				default:
 					$ns = $prop['ns'];
 			}
-			// allow multiple values for same name
-			if (isset($arr[$ns.':'.$prop['name']]))
-			{
-				$arr[$ns.':'.$prop['name']] = (array)$arr[$ns.':'.$prop['name']];
-				$arr[$ns.':'.$prop['name']][] = $prop['val'];
-			}
-			else
-			{
-				$arr[$ns.':'.$prop['name']] = $prop['val'];
-			}
+			$arr[$ns.':'.$prop['name']] = is_array($prop['val']) ? 
+				$this->_hierarchical_prop_encode($prop['val']) : $prop['val'];
 		}
 		return $arr;
 	}