diff --git a/xml/Makefile.am b/xml/Makefile.am
index 3453b4b34b..12a51c5c90 100644
--- a/xml/Makefile.am
+++ b/xml/Makefile.am
@@ -1,293 +1,297 @@
 #
 # Copyright 2004-2021 the Pacemaker project contributors
 #
 # The version control history for this file may have further details.
 #
 # This source code is licensed under the GNU General Public License version 2
 # or later (GPLv2+) WITHOUT ANY WARRANTY.
 #
 
 include $(top_srcdir)/mk/common.mk
 
 noarch_pkgconfig_DATA	= $(builddir)/pacemaker-schemas.pc
 
 # Pacemaker has 3 schemas: the CIB schema, the API schema (for command-line
 # tool XML output), and a legacy schema for crm_mon --as-xml.
 #
 # See README.md for details on updating CIB schema files (API is similar)
 
 # The CIB and crm_mon schemas are installed directly in CRM_SCHEMA_DIRECTORY
 # for historical reasons, while the API schema is installed in a subdirectory.
 APIdir	= $(CRM_SCHEMA_DIRECTORY)/api
 CIBdir	= $(CRM_SCHEMA_DIRECTORY)
 MONdir	= $(CRM_SCHEMA_DIRECTORY)
 
 # Extract a sorted list of available numeric schema versions
 # from filenames like NAME-MAJOR[.MINOR][.MINOR-MINOR].rng
 numeric_versions = $(shell ls -1 $(1) \
 			  | sed -n -e 's/^.*-\([0-9][0-9.]*\).rng$$/\1/p' \
 			  | sort -u -t. -k 1,1n -k 2,2n -k 3,3n)
 
 version_pairs = $(join \
 			    $(1),$(addprefix \
 			      -,$(wordlist \
 			        2,$(words $(1)),$(1) \
 			      ) next \
 			    ) \
 			  )
 
 version_pairs_last = $(wordlist \
 			    $(words \
 			      $(wordlist \
 			        2,$(1),$(2) \
 			      ) \
 			    ),$(1),$(2) \
 			  )
 
 # NOTE: All files in API_request_base, CIB_cfg_base, API_base, and CIB_base
 # need to start with a unique prefix.  These variables all get iterated over
 # and globbed, and two files starting with the same prefix will cause
 # problems.
 
 # Names of API schemas that form the choices for pacemaker-result content
 API_request_base	= command-output	\
 			  crm_mon		\
 			  crm_resource		\
 			  crm_simulate		\
 			  crmadmin		\
 			  digests		\
 			  stonith_admin		\
 			  version
 
 # Names of CIB schemas that form the choices for cib/configuration content
 CIB_cfg_base		= options nodes resources constraints fencing acls tags alerts
 
 # Names of all schemas (including top level and those included by others)
 API_base		= $(API_request_base) fence-event failure generic-list item node-attrs nodes resources status
 CIB_base		= cib $(CIB_cfg_base) status score rule nvset
 
 # Static schema files and transforms (only CIB has transforms)
 # 
 # This is more complicated than it should be due to the need to support
 # VPATH builds and "make distcheck". We need the absolute paths for reliable
 # substitution back and forth, and relative paths for distributed files.
 API_abs_files		= $(foreach base,$(API_base),$(wildcard $(abs_srcdir)/api/$(base)-*.rng))
 CIB_abs_files		= $(foreach base,$(CIB_base),$(wildcard $(abs_srcdir)/$(base).rng $(abs_srcdir)/$(base)-*.rng))
 CIB_abs_xsl		= $(abs_srcdir)/upgrade-1.3.xsl			\
 			  $(abs_srcdir)/upgrade-2.10.xsl		\
 			  $(wildcard $(abs_srcdir)/upgrade-*enter.xsl)	\
 			  $(wildcard $(abs_srcdir)/upgrade-*leave.xsl)
 MON_abs_files 		= $(abs_srcdir)/crm_mon.rng
 API_files		= $(foreach base,$(API_base),$(wildcard $(srcdir)/api/$(base)-*.rng))
 CIB_files		= $(foreach base,$(CIB_base),$(wildcard $(srcdir)/$(base).rng $(srcdir)/$(base)-*.rng))
 CIB_xsl			= $(srcdir)/upgrade-1.3.xsl			\
 			  $(srcdir)/upgrade-2.10.xsl		\
 			  $(wildcard $(srcdir)/upgrade-*enter.xsl)	\
 			  $(wildcard $(srcdir)/upgrade-*leave.xsl)
 MON_files 		= $(srcdir)/crm_mon.rng
 
 # Sorted lists of all numeric schema versions
 API_numeric_versions	= $(call numeric_versions,${API_files})
 CIB_numeric_versions	= $(call numeric_versions,${CIB_files})
 MON_numeric_versions 	= $(call numeric_versions,$(wildcard $(srcdir)/api/crm_mon*.rng))
 
 # The highest numeric schema version
 API_max			?= $(lastword $(API_numeric_versions))
 CIB_max			?= $(lastword $(CIB_numeric_versions))
 MON_max 			?= $(lastword $(MON_numeric_versions))
 
 # Sorted lists of all schema versions (including "next")
 API_versions		= next $(API_numeric_versions)
 CIB_versions		= next $(CIB_numeric_versions)
 
 # Build tree locations of static schema files and transforms (for VPATH builds)
 API_build_copies	= $(foreach f,$(API_abs_files),$(subst $(abs_srcdir),$(abs_builddir),$(f)))
 CIB_build_copies	= $(foreach f,$(CIB_abs_files) $(CIB_abs_xsl),$(subst $(abs_srcdir),$(abs_builddir),$(f)))
 MON_build_copies 	= $(foreach f,$(MON_abs_files),$(subst $(abs_srcdir),$(abs_builddir),$(f)))
 
 # Dynamically generated schema files
 API_generated		= api/api-result.rng $(foreach base,$(API_versions),api/api-result-$(base).rng)
 CIB_generated		= pacemaker.rng $(foreach base,$(CIB_versions),pacemaker-$(base).rng) versions.rng
 MON_generated 		= crm_mon.rng
 
 CIB_version_pairs	= $(call version_pairs,${CIB_numeric_versions})
 CIB_version_pairs_cnt	= $(words ${CIB_version_pairs})
 CIB_version_pairs_last  = $(call version_pairs_last,${CIB_version_pairs_cnt},${CIB_version_pairs})
 
 dist_API_DATA		= $(API_files)
 dist_CIB_DATA		= $(CIB_files) $(CIB_xsl)
 
 nodist_API_DATA		= $(API_generated)
 nodist_CIB_DATA		= $(CIB_generated)
 nodist_MON_DATA		= $(MON_generated)
 
 EXTRA_DIST		= README.md			\
 			  best-match.sh			\
 			  cibtr-2.rng			\
 			  context-of.xsl		\
 			  ocf-meta2man.xsl		\
 			  regression.sh			\
 			  upgrade-2.10-roundtrip.xsl	\
 			  upgrade-detail.xsl		\
 			  xslt_cibtr-2.rng		\
 			  assets			\
 			  test-2			\
 			  test-2-enter			\
 			  test-2-leave			\
 			  test-2-roundtrip
 
 cib-versions:
 	@echo "Max: $(CIB_max)"
 	@echo "Available: $(CIB_versions)"
 
 api-versions:
 	@echo "Max: $(API_max)"
 	@echo "Available: $(API_versions)"
 
 # Dynamically generated top-level API schema
 api/api-result.rng: api/api-result-$(API_max).rng
 	$(AM_V_at)$(MKDIR_P) api # might not exist in VPATH build
 	$(AM_V_SCHEMA)cp $(top_builddir)/xml/$< $@
 
 api/api-result-%.rng: $(API_build_copies) best-match.sh Makefile.am
 	$(AM_V_at)echo '<?xml version="1.0" encoding="UTF-8"?>' > $@
 	$(AM_V_at)echo '<grammar xmlns="http://relaxng.org/ns/structure/1.0" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">' >> $@
 	$(AM_V_at)echo '  <start>' >> $@
 	$(AM_V_at)echo '    <element name="pacemaker-result">' >> $@
 	$(AM_V_at)echo '      <attribute name="api-version"> <text /> </attribute>' >> $@
 	$(AM_V_at)echo '      <attribute name="request"> <text /> </attribute>' >> $@
 	$(AM_V_at)echo '      <optional>' >> $@
 	$(AM_V_at)echo '        <choice>' >> $@
 	$(AM_V_at)for rng in $(API_request_base); do $(srcdir)/best-match.sh api/$$rng $(*) $(@) "          " || :; done
 	$(AM_V_at)echo '        </choice>' >> $@
 	$(AM_V_at)echo '      </optional>' >> $@
 	$(AM_V_at)$(srcdir)/best-match.sh api/status $(*) $(@) "      " || :
 	$(AM_V_at)echo '    </element>' >> $@
 	$(AM_V_at)echo '  </start>' >> $@
 	$(AM_V_SCHEMA)echo '</grammar>' >> $@
 
 crm_mon.rng: api/crm_mon-$(MON_max).rng
 	$(AM_V_at)echo '<?xml version="1.0" encoding="UTF-8"?>' > $@
 	$(AM_V_at)echo '<grammar xmlns="http://relaxng.org/ns/structure/1.0"' >> $@
 	$(AM_V_at)echo '         datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">' >> $@
 	$(AM_V_at)echo '    <start>' >> $@
 	$(AM_V_at)echo '        <ref name="element-crm_mon-old"/>' >> $@
 	$(AM_V_at)echo '    </start>' >> $@
 	$(AM_V_at)echo '    <define name="element-crm_mon-old">' >> $@
 	$(AM_V_at)echo '        <element name="crm_mon">' >> $@
 	$(AM_V_at)echo '            <attribute name="version"> <text/> </attribute>' >> $@
 	$(AM_V_at)echo '            <externalRef href="$(<)" />' >> $@
 	$(AM_V_at)echo '        </element>' >> $@
 	$(AM_V_at)echo '    </define>' >> $@
 	$(AM_V_SCHEMA)echo '</grammar>' >> $@
 
 # Dynamically generated top-level CIB schema
 pacemaker.rng: pacemaker-$(CIB_max).rng
 	$(AM_V_SCHEMA)cp $(top_builddir)/xml/$< $@
 
 pacemaker-%.rng: $(CIB_build_copies) best-match.sh Makefile.am
 	$(AM_V_at)echo '<?xml version="1.0" encoding="UTF-8"?>' > $@
 	$(AM_V_at)echo '<grammar xmlns="http://relaxng.org/ns/structure/1.0" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">' >> $@
 	$(AM_V_at)echo '  <start>' >> $@
 	$(AM_V_at)echo '    <element name="cib">' >> $@
 	$(AM_V_at)$(srcdir)/best-match.sh cib $(*) $(@) "      "
 	$(AM_V_at)echo '      <element name="configuration">' >> $@
 	$(AM_V_at)echo '        <interleave>' >> $@
 	$(AM_V_at)for rng in $(CIB_cfg_base); do $(srcdir)/best-match.sh $$rng $(*) $(@) "          " || :; done
 	$(AM_V_at)echo '        </interleave>' >> $@
 	$(AM_V_at)echo '      </element>' >> $@
 	$(AM_V_at)echo '      <optional>' >> $@
 	$(AM_V_at)echo '        <element name="status">' >> $@
 	$(AM_V_at)$(srcdir)/best-match.sh status $(*) $(@) "          "
 	$(AM_V_at)echo '        </element>' >> $@
 	$(AM_V_at)echo '      </optional>' >> $@
 	$(AM_V_at)echo '    </element>' >> $@
 	$(AM_V_at)echo '  </start>' >> $@
 	$(AM_V_SCHEMA)echo '</grammar>' >> $@
 
 # Dynamically generated CIB schema listing all pacemaker versions
 versions.rng: Makefile.am
 	$(AM_V_at)echo '<?xml version="1.0" encoding="UTF-8"?>' > $@
 	$(AM_V_at)echo '<grammar xmlns="http://relaxng.org/ns/structure/1.0" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">' >> $@
 	$(AM_V_at)echo '  <start>' >> $@
 	$(AM_V_at)echo '   <interleave>' >> $@
 	$(AM_V_at)echo '    <optional>' >> $@
 	$(AM_V_at)echo '      <attribute name="validate-with">' >> $@
 	$(AM_V_at)echo '        <choice>' >> $@
 	$(AM_V_at)echo '          <value>none</value>' >> $@
 	$(AM_V_at)echo '          <value>pacemaker-0.6</value>' >> $@
 	$(AM_V_at)echo '          <value>transitional-0.6</value>' >> $@
 	$(AM_V_at)echo '          <value>pacemaker-0.7</value>' >> $@
 	$(AM_V_at)echo '          <value>pacemaker-1.1</value>' >> $@
 	$(AM_V_at)for rng in $(CIB_versions); do echo "          <value>pacemaker-$$rng</value>" >> $@; done
 	$(AM_V_at)echo '        </choice>' >> $@
 	$(AM_V_at)echo '      </attribute>' >> $@
 	$(AM_V_at)echo '    </optional>' >> $@
 	$(AM_V_at)echo '    <attribute name="admin_epoch"><data type="nonNegativeInteger"/></attribute>' >> $@
 	$(AM_V_at)echo '    <attribute name="epoch"><data type="nonNegativeInteger"/></attribute>' >> $@
 	$(AM_V_at)echo '    <attribute name="num_updates"><data type="nonNegativeInteger"/></attribute>' >> $@
 	$(AM_V_at)echo '   </interleave>' >> $@
 	$(AM_V_at)echo '  </start>' >> $@
 	$(AM_V_SCHEMA)echo '</grammar>' >> $@
 
 # diff fails with ec=2 if no predecessor is found;
 # this uses '=' GNU extension to sed, if that's not available,
 # one can use: hline=`echo "$${p}" | grep -Fn "$${hunk}" | cut -d: -f1`;
 # XXX: use line information from hunk to avoid "not detected" for ambiguity
 version_diff = \
 	@for p in $(1); do \
 	  set `echo "$${p}" | tr '-' ' '`; \
 	  echo "\#\#\# *-$$2.rng vs. predecessor"; \
 	  for v in *-$$2.rng; do \
 	    echo "\#\#\#\# $${v} vs. predecessor"; b=`echo "$${v}" | cut -d- -f1`; \
 	    old=`./best-match.sh $${b} $$1`; \
 	    p=`diff -u "$${old}" "$${v}" 2>/dev/null`; \
 	    case $$? in \
 	    1) echo "$${p}" | sed -n -e '/^@@ /!d;=;p' \
 	       -e ':l;n;/^\([- ]\|+.*<[^ />]\+\([^/>]\+="ID\|>$$\)\)/bl;s/^[+ ]\(.*\)/\1/p' \
 	       | while read hline; do \
 	           read h && read i || break; \
 	           iline=`grep -Fn "$${i}" "$${v}" | cut -d: -f1`; \
 	           ctxt="(not detected)"; \
 	           if test `echo "$${iline}" | wc -l` -eq 1; then \
 	             ctxt=`{ sed -n -e "1,$$(($${iline}-1))p" "$${v}"; \
 	                     echo "<inject id=\"GOAL\"/>$${i}"; \
 	                     sed -n -e "$$(($${iline}+1)),$$ p" "$${v}"; \
 	                   } | $(XSLTPROC) --param skip 1 context-of.xsl -`; \
 	           fi; \
 	           echo "$${p}" | sed -n -e "$$(($${hline}-2)),$${hline}!d" \
 	             -e '/^\(+++\|---\)/p'; \
 	           echo "$${h} context: $${ctxt}"; \
 	           echo "$${p}" | sed -n -e "1,$${hline}d" \
 	             -e '/^\(---\|@@ \)/be;p;d;:e;n;be'; \
 	           done; \
 	       ;; \
 	    2) echo "\#\#\#\#\# $${v} has no predecessor";; \
 	    esac; \
 	  done; \
 	done
 
 diff: best-match.sh
 	@echo "#  Comparing changes in + since $(CIB_max)"
 	$(call version_diff,${CIB_version_pairs_last})
 
 fulldiff: best-match.sh
 	@echo "#  Comparing all changes across all the subsequent increments"
 	$(call version_diff,${CIB_version_pairs})
 
 CLEANFILES = $(API_generated) $(CIB_generated) $(MON_generated)
 
+# Remove pacemaker schema files generated by *any* source version. This allows
+# "make -C xml clean" to have the desired effect when checking out an earlier
+# revision in a source tree.
 clean-local:
 	if [ "x$(srcdir)" != "x$(builddir)" ]; then					\
 		rm -f $(API_build_copies) $(CIB_build_copies) $(MON_build_copies);	\
 	fi
+	rm -f $(builddir)/pacemaker-[0-9]*.[0-9]*.rng
 
 # Enable ability to use $@ in prerequisite
 .SECONDEXPANSION:
 
 # For VPATH builds, copy the static schema files into the build tree
 $(API_build_copies) $(CIB_build_copies) $(MON_build_copies): $$(subst $(abs_builddir),$(srcdir),$$(@))
 	$(AM_V_GEN)if [ "x$(srcdir)" != "x$(builddir)" ]; then	\
 		$(MKDIR_P) "$(dir $(@))";			\
 		cp "$(<)" "$(@)";				\
 	fi