diff --git a/xml/upgrade-2.10.xsl b/xml/upgrade-2.10.xsl
index d1e7f4725e..d956582f6a 100644
--- a/xml/upgrade-2.10.xsl
+++ b/xml/upgrade-2.10.xsl
@@ -1,136 +1,163 @@
 <!--
  Copyright 2018 Red Hat, Inc.
  Author: Jan Pokorny <jpokorny@redhat.com>
  Part of pacemaker project
  SPDX-License-Identifier: GPL-2.0-or-later
  -->
 <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                 xmlns:cibtr="http://clusterlabs.org/ns/pacemaker/cibtr-2">
 <xsl:output method="xml" encoding="UTF-8" indent="yes" omit-xml-declaration="yes"/>
 
 <xsl:param name="cib-min-ver" select="'3.0'"/>
 
 <!--
- helper definitions
+
+ HELPER DEFINITIONS
+
  -->
 
 <cibtr:map>
 
   <!--
    Target tag:     rsc_colocation
    Object:         ./@*
    -->
   <cibtr:table for="constraints-colocation" msg-prefix="Constraints-colocation">
     <cibtr:replace what="score-attribute"
                    with=""
                    msg-extra="was actually never in effect"/>
     <cibtr:replace what="score-attribute-mangle"
                    with=""
                    msg-extra="was actually never in effect"/>
   </cibtr:table>
 
 </cibtr:map>
 
 <xsl:variable name="MapConstraintsColocation"
               select="document('')/xsl:stylesheet
                         /cibtr:map/cibtr:table[
                           @for = 'constraints-colocation'
                         ]"/>
 
+<!--
+
+ GENERIC UTILITIES
+
+ -->
+
+<!--
+ Plain identity template
+
+ Merely implicit-context-driven, no arguments.
+ -->
+<xsl:template name="HelperIdentity">
+  <xsl:copy>
+    <xsl:apply-templates select="@*|node()"/>
+  </xsl:copy>
+</xsl:template>
+
+<!--
+ Emit an message about the replacement, sanity checking the source definitions
+
+ Merely parameter driven, no implicit context taken into account:
+ - Context: optional message prefix
+ - Replacement: selected subset of cibtr:map's leaves
+                (it's considered a hard error if consists of more than 1 item)
+ -->
 <xsl:template name="MapMsg">
   <xsl:param name="Context" select="''"/>
   <xsl:param name="Replacement"/>
   <xsl:choose>
     <xsl:when test="not($Replacement)"/>
     <xsl:when test="count($Replacement) != 1">
       <xsl:message terminate="yes">
         <xsl:value-of select="concat('INTERNAL ERROR:',
                                      $Replacement/../@msg-prefix,
                                      ': count($Replacement) != 1',
                                      ' does not hold (',
                                      count($Replacement), ')')"/>
       </xsl:message>
     </xsl:when>
     <xsl:otherwise>
       <xsl:variable name="MsgPrefix" select="concat(
                                                ($Replacement|$Replacement/..)
                                                  /@msg-prefix, ': '
                                              )"/>
       <xsl:message>
         <xsl:value-of select="$MsgPrefix"/>
         <xsl:if test="$Context">
           <xsl:value-of select="concat($Context, ': ')"/>
         </xsl:if>
         <xsl:choose>
           <xsl:when test="string($Replacement/@with)">
             <xsl:value-of select="concat('renaming ', $Replacement/@what,
                                          ' as ', $Replacement/@with)"/>
           </xsl:when>
           <xsl:otherwise>
             <xsl:value-of select="concat('dropping ', $Replacement/@what)"/>
           </xsl:otherwise>
         </xsl:choose>
       </xsl:message>
       <xsl:if test="$Replacement/@msg-extra">
         <xsl:message>
           <xsl:value-of select="concat($MsgPrefix, '... ',
                                        $Replacement/@msg-extra)"/>
         </xsl:message>
       </xsl:if>
     </xsl:otherwise>
   </xsl:choose>
 </xsl:template>
 
 <!--
- actual transformation
+
+ ACTUAL TRANSFORMATION
+
  -->
 
 <xsl:template match="cib">
   <xsl:copy>
     <xsl:apply-templates select="@*"/>
     <xsl:attribute name="validate-with">
       <xsl:value-of select="concat('pacemaker-', $cib-min-ver)"/>
     </xsl:attribute>
     <xsl:apply-templates select="node()"/>
   </xsl:copy>
 </xsl:template>
 
 <xsl:template match="rsc_colocation">
   <xsl:copy>
     <xsl:for-each select="@*">
       <xsl:variable name="Replacement"
                     select="$MapConstraintsColocation/cibtr:replace[
                               @what = name(current())
                             ]"/>
       <xsl:call-template name="MapMsg">
         <xsl:with-param name="Context" select="../@id"/>
         <xsl:with-param name="Replacement" select="$Replacement"/>
       </xsl:call-template>
       <xsl:choose>
         <xsl:when test="$Replacement
                         and
                         not(string($Replacement/@with))">
           <!-- drop -->
         </xsl:when>
         <xsl:when test="$Replacement">
           <!-- rename -->
           <xsl:attribute name="{name()}">
             <xsl:value-of select="$Replacement/@with"/>
           </xsl:attribute>
         </xsl:when>
         <xsl:otherwise>
           <xsl:copy/>
         </xsl:otherwise>
       </xsl:choose>
     </xsl:for-each>
     <xsl:apply-templates select="node()"/>
   </xsl:copy>
 </xsl:template>
 
 <xsl:template match="@*|node()">
-  <xsl:copy>
-    <xsl:apply-templates select="@*|node()"/>
-  </xsl:copy>
+  <xsl:call-template name="HelperIdentity"/>
 </xsl:template>
 
 </xsl:stylesheet>