diff --git a/xml/crm_mon.rng b/xml/crm_mon.rng
index 008c3ef6fa..653c15e9d1 100644
--- a/xml/crm_mon.rng
+++ b/xml/crm_mon.rng
@@ -1,301 +1,301 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <grammar xmlns="http://relaxng.org/ns/structure/1.0" 
          datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
 
     <start>
         <ref name="element-crm_mon"/>
     </start>
 
     <define name="element-crm_mon">
         <element name="crm_mon">
             <attribute name="version"> <text/> </attribute>
             <element name="summary">
                 <interleave>
                     <optional>
                         <element name="last_update">
                             <!-- crm_mon shows dates like "Mon Apr 13 16:06:27 2015" not
                                  the XSD dateTime like "2015-04-13T16:06:27-05:00" -->
                             <attribute name="time"> <text/> </attribute>
                         </element>
                     </optional>
                     <optional>
                         <element name="last_change">
                             <attribute name="time"> <text/> </attribute>
                             <attribute name="user"> <text/> </attribute>
                             <attribute name="client"> <text/> </attribute>
                             <attribute name="origin"> <text/> </attribute>
                         </element>
                     </optional>
                     <optional>
                         <element name="stack">
                             <attribute name="type"> <text/> </attribute>
                         </element>
                     </optional>
                     <element name="current_dc">
                         <attribute name="present"> <data type="boolean" /> </attribute>
                         <optional>
                             <group>
                                 <attribute name="version"> <text/> </attribute>
                                 <attribute name="name"> <text/> </attribute>
                                 <!-- pacemaker IDs are user-defined strings that are
                                      not as restricted as the XSD ID type -->
                                 <attribute name="id"> <text/> </attribute>
                                 <attribute name="with_quorum"> <data type="boolean" /> </attribute>
                             </group>
                         </optional>
                     </element>
                     <element name="nodes_configured">
                         <attribute name="number"> <data type="int" /> </attribute>
                         <choice>
                             <attribute name="expected_votes"> <data type="int" /> </attribute>
                             <attribute name="expected_votes"> <value>unknown</value> </attribute>
                         </choice>
                     </element>
                     <element name="resources_configured">
                         <attribute name="number"> <data type="int" /> </attribute>
                         <optional>
                             <attribute name="disabled"> <data type="int" /> </attribute>
                             <attribute name="blocked"> <data type="int" /> </attribute>
                         </optional>
                     </element>
                     <optional>
                         <element name="cluster_options">
                             <attribute name="stonith-enabled"> <data type="boolean" /> </attribute>
                             <attribute name="symmetric-cluster"> <data type="boolean" /> </attribute>
                             <attribute name="no-quorum-policy"> <text/> </attribute>
                             <optional>
                                 <attribute name="maintenance-mode"> <data type="boolean" /> </attribute>
                             </optional>
                         </element>
                     </optional>
                 </interleave>
             </element>
             <element name="nodes">
                 <zeroOrMore>
                     <element name="node">
                         <attribute name="name"> <text/> </attribute>
                         <attribute name="id"> <text/> </attribute>
                         <attribute name="online"> <data type="boolean" /> </attribute>
                         <attribute name="standby"> <data type="boolean" /> </attribute>
                         <attribute name="standby_onfail"> <data type="boolean" /> </attribute>
                         <attribute name="maintenance"> <data type="boolean" /> </attribute>
                         <attribute name="pending"> <data type="boolean" /> </attribute>
                         <attribute name="unclean"> <data type="boolean" /> </attribute>
                         <attribute name="shutdown"> <data type="boolean" /> </attribute>
                         <attribute name="expected_up"> <data type="boolean" /> </attribute>
                         <attribute name="is_dc"> <data type="boolean" /> </attribute>
                         <attribute name="resources_running"> <data type="int" /> </attribute>
                         <attribute name="type">
                             <choice>
                                 <value>unknown</value>
                                 <value>member</value>
                                 <value>remote</value>
                                 <value>ping</value>
                             </choice>
                         </attribute>
                         <optional>
                             <!-- for virtualized pacemaker_remote nodes, crm_mon 1.1.13 uses
                                  "container_id" while later versions use "id_as_resource" -->
                             <choice>
                                 <attribute name="container_id"> <text/> </attribute>
                                 <attribute name="id_as_resource"> <text/> </attribute>
                             </choice>
                         </optional>
                         <ref name="resource_list" />
                     </element>
                 </zeroOrMore>
             </element>
             <optional>
                 <element name="resources">
                     <ref name="resource_list" />
                 </element>
             </optional>
             <optional>
                 <element name="node_attributes">
                     <zeroOrMore>
                         <element name="node">
                             <attribute name="name"> <text/> </attribute>
                             <zeroOrMore>
                                 <element name="attribute">
                                     <attribute name="name"> <text/> </attribute>
                                     <attribute name="value"> <text/> </attribute>
                                     <optional>
                                         <attribute name="expected"> <data type="int" /> </attribute>
                                     </optional>
                                 </element>
                             </zeroOrMore>
                         </element>
                     </zeroOrMore>
                 </element>
             </optional>
             <optional>
                 <element name="node_history">
                     <zeroOrMore>
                         <element name="node">
                             <attribute name="name"> <text/> </attribute>
                             <zeroOrMore>
                                 <element name="resource_history">
                                     <attribute name="id"> <text/> </attribute>
                                     <attribute name="orphan"> <data type="boolean" /> </attribute>
                                     <attribute name="migration-threshold"> <data type="int" /> </attribute>
                                     <optional>
                                         <attribute name="fail-count"> <data type="int" /> </attribute>
                                     </optional>
                                     <optional>
                                         <attribute name="last-failure"> <text/> </attribute>
                                     </optional>
                                     <zeroOrMore>
                                         <element name="operation_history">
                                             <attribute name="call"> <text/> </attribute>
                                             <attribute name="task"> <text/> </attribute>
                                             <optional>
                                                 <attribute name="interval"> <text/> </attribute>
                                             </optional>
                                             <optional>
                                                 <attribute name="last-rc-change"> <text/> </attribute>
                                             </optional>
                                             <optional>
                                                 <attribute name="last-run"> <text/> </attribute>
                                             </optional>
                                             <optional>
                                                 <attribute name="exec-time"> <text/> </attribute>
                                             </optional>
                                             <optional>
                                                 <attribute name="queue-time"> <text/> </attribute>
                                             </optional>
                                             <attribute name="rc"> <data type="int" /> </attribute>
                                             <attribute name="rc_text"> <text/> </attribute>
                                         </element>
                                     </zeroOrMore>
                                 </element>
                             </zeroOrMore>
                         </element>
                     </zeroOrMore>
                 </element>
             </optional>
             <optional>
                 <element name="failures">
                     <zeroOrMore>
                         <element name="failure">
                             <choice>
                                 <attribute name="op_key"> <text/> </attribute>
                                 <attribute name="id"> <text/> </attribute>
                             </choice>
                             <attribute name="node"> <text/> </attribute>
                             <attribute name="exitstatus"> <text/> </attribute>
                             <attribute name="exitreason"> <text/> </attribute>
                             <attribute name="exitcode"> <data type="int" /> </attribute>
                             <attribute name="call"> <text/> </attribute>
                             <attribute name="status"> <text/> </attribute>
                             <optional>
                                 <group>
                                     <attribute name="last-rc-change"> <text/> </attribute>
                                     <attribute name="queued"> <text/> </attribute>
                                     <attribute name="exec"> <text/> </attribute>
                                     <attribute name="interval"> <data type="int" />  </attribute>
                                     <attribute name="task"> <text/> </attribute>
                                 </group>
                             </optional>
                         </element>
                     </zeroOrMore>
                 </element>
             </optional>
             <optional>
                 <element name="tickets">
                     <zeroOrMore>
                         <element name="ticket">
                             <attribute name="id"> <text/> </attribute>
                             <attribute name="status"> <text/> </attribute>
                             <attribute name="standby"> <data type="boolean" /> </attribute>
                             <optional>
                                 <attribute name="last-granted"> <text/> </attribute>
                             </optional>
                         </element>
                     </zeroOrMore>
                 </element>
             </optional>
             <optional>
                 <element name="bans">
                     <zeroOrMore>
                         <element name="ban">
                             <attribute name="id"> <text/> </attribute>
                             <attribute name="resource"> <text/> </attribute>
                             <attribute name="node"> <text/> </attribute>
                             <attribute name="weight"> <data type="int" />  </attribute>
                             <attribute name="master_only"> <data type="boolean" /> </attribute>
                         </element>
                     </zeroOrMore>
                 </element>
             </optional>
         </element>
     </define>
 
     <define name="resource_list">
         <interleave>
             <zeroOrMore>
                 <ref name="element-resource" />
             </zeroOrMore>
             <zeroOrMore>
                 <ref name="element-group" />
             </zeroOrMore>
             <zeroOrMore>
                 <ref name="element-clone" />
             </zeroOrMore>
         </interleave>
     </define>
 
     <define name="element-resource">
         <element name="resource">
             <attribute name="id"> <text/> </attribute>
             <attribute name="resource_agent"> <text/> </attribute>
             <attribute name="role"> <text/> </attribute>
             <optional>
                 <attribute name="target_role"> <text/> </attribute>
             </optional>
             <attribute name="active"> <data type="boolean" /> </attribute>
             <attribute name="orphaned"> <data type="boolean" /> </attribute>
             <optional>
                 <attribute name="blocked"> <data type="boolean" /> </attribute>
             </optional>
             <attribute name="managed"> <data type="boolean" /> </attribute>
             <attribute name="failed"> <data type="boolean" /> </attribute>
             <attribute name="failure_ignored"> <data type="boolean" /> </attribute>
             <attribute name="nodes_running_on"> <data type="int" />  </attribute>
             <optional>
                 <attribute name="pending"> <text/> </attribute>
             </optional>
-            <optional>
+            <zeroOrMore>
                 <!-- crm_mon prints the node only if group-by-node is false -->
                 <element name="node">
                     <attribute name="name"> <text/> </attribute>
                     <attribute name="id"> <text/> </attribute>
                     <attribute name="cached"> <data type="boolean" /> </attribute>
                 </element>
-            </optional>
+            </zeroOrMore>
         </element>
     </define>
 
     <define name="element-group">
         <element name="group">
             <attribute name="id"> <text/> </attribute>
             <attribute name="number_resources"> <data type="int" /> </attribute>
             <ref name="resource_list" />
         </element>
     </define>
 
     <define name="element-clone">
         <element name="clone">
             <attribute name="id"> <text/> </attribute>
             <attribute name="multi_state"> <data type="boolean" /> </attribute>
             <attribute name="unique"> <data type="boolean" /> </attribute>
             <attribute name="managed"> <data type="boolean" /> </attribute>
             <attribute name="failed"> <data type="boolean" /> </attribute>
             <attribute name="failure_ignored"> <data type="boolean" /> </attribute>
             <optional>
                 <attribute name="target_role"> <text/> </attribute>
             </optional>
             <ref name="resource_list" />
         </element>
     </define>
 
 </grammar>