diff --git a/xep-0171.xml b/xep-0171.xml
index 451b8c07..34ed857f 100644
--- a/xep-0171.xml
+++ b/xep-0171.xml
@@ -50,6 +50,12 @@
     <surname>Raymond</surname>
     <email>braymond@echostorm.net</email>
   </author>
+  <revision>
+    <version>1.1.1</version>
+    <date>2015-10-15</date>
+    <initials>XEP Editor (mam)</initials>
+    <remark><p>Corrected XML schema to note a number of constructs are optional not required (Christian Schudt).</p></remark>
+  </revision>
   <revision>
     <version>1.1</version>
     <date>2011-06-15</date>
@@ -416,7 +422,7 @@
 
   <xs:element name='x'>
     <xs:complexType>
-      <xs:element ref='source' use='required'/>
+      <xs:element ref='source' use='optional'/>
       <xs:sequence>
         <xs:element ref='translation' use='required' minOccurs='1'/>
       </xs:sequence>
@@ -439,8 +445,8 @@
         <xs:extension base='empty'>
           <xs:attribute name='charset' type='xs:string' use='optional'/>
           <xs:attribute name='source_lang' type='xs:language' use='optional' />
-          <xs:attribute name='destination_lang' type='xs:string' use='required'/>
-          <xs:attribute name='dictionary' type='xs:string' use='required'/>
+          <xs:attribute name='destination_lang' type='xs:language' use='required'/>
+          <xs:attribute name='dictionary' type='xs:string' use='optional'/>
           <xs:attribute name='engine' type='xs:string' use='optional' />
           <xs:attribute name='reviewed' type='xs:boolean' use='optional' default='false'/>
         </xs:extension>