diff --git a/doc/.gitignore b/doc/.gitignore
index 41a38f87..0f27c4db 100644
--- a/doc/.gitignore
+++ b/doc/.gitignore
@@ -1,10 +1,9 @@
 HTML.index
-bookindex.sgml
+bookindex.xml
 html-stamp
 html/
-nochunks.dsl
 repmgr.html
-version.sgml
+version.xml
 *.fo
 *.pdf
 
diff --git a/doc/Makefile b/doc/Makefile
index b8d07e22..99540245 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -24,11 +24,11 @@ endif
 
 override XSLTPROCFLAGS += --stringparam repmgr.version '$(REPMGR_VERSION)'
 
-GENERATED_SGML = version.sgml
-ALLSGML := $(wildcard $(srcdir)/*.sgml) $(GENERATED_SGML)
+GENERATED_XML = version.xml
+ALLXML := $(wildcard $(srcdir)/*.xml) $(GENERATED_XML)
 
 
-version.sgml: $(repmgr_top_builddir)/repmgr_version.h
+version.xml: $(repmgr_top_builddir)/repmgr_version.h
 	{ \
 	  echo "<!ENTITY repmgrversion \"$(REPMGR_VERSION)\">"; \
 	} > $@
@@ -40,14 +40,14 @@ version.sgml: $(repmgr_top_builddir)/repmgr_version.h
 
 html: html-stamp
 
-html-stamp: stylesheet.xsl repmgr.sgml $(ALLSGML)
+html-stamp: stylesheet.xsl repmgr.xml $(ALLXML)
 	$(XMLLINT) $(XMLINCLUDE) --noout --valid $(word 2,$^)
 	$(XSLTPROC) $(XMLINCLUDE) $(XSLTPROCFLAGS) $(XSLTPROC_HTML_FLAGS) $(wordlist 1,2,$^)
 	cp $(srcdir)/stylesheet.css  $(srcdir)/website-docs.css html/
 	touch $@
 
 # single-page HTML
-repmgr.html: stylesheet-html-nochunk.xsl repmgr.sgml $(ALLSGML)
+repmgr.html: stylesheet-html-nochunk.xsl repmgr.xml $(ALLXML)
 	$(XMLLINT) $(XMLINCLUDE) --noout --valid $(word 2,$^)
 	$(XSLTPROC) $(XMLINCLUDE) $(XSLTPROCFLAGS) $(XSLTPROC_HTML_FLAGS) -o $@ $(wordlist 1,2,$^)
 
@@ -66,7 +66,7 @@ repmgr.pdf:
 
 # Standard paper size
 
-repmgr-A4.fo: stylesheet-fo.xsl repmgr.sgml $(ALLSGML)
+repmgr-A4.fo: stylesheet-fo.xsl repmgr.xml $(ALLXML)
 	$(XMLLINT) $(XMLINCLUDE) --noout --valid $(word 2,$^)
 	$(XSLTPROC) $(XMLINCLUDE) $(XSLTPROCFLAGS) --stringparam paper.type A4 -o $@ $(wordlist 1,2,$^)
 
@@ -75,7 +75,7 @@ repmgr-A4.pdf: repmgr-A4.fo
 
 # North American paper size
 
-repmgr-US.fo: stylesheet-fo.xsl repmgr.sgml $(ALLSGML)
+repmgr-US.fo: stylesheet-fo.xsl repmgr.xml $(ALLXML)
 	$(XMLLINT) $(XMLINCLUDE) --noout --valid $(word 2,$^)
 	$(XSLTPROC) $(XMLINCLUDE) $(XSLTPROCFLAGS) --stringparam paper.type USletter -o $@ $(wordlist 1,2,$^)
 
@@ -90,7 +90,7 @@ install: html
 
 clean:
 	rm -f html-stamp
-	rm -f HTML.index $(GENERATED_SGML)
+	rm -f HTML.index $(GENERATED_XML)
 
 maintainer-clean:
 	rm -rf html
diff --git a/doc/appendix-faq.sgml b/doc/appendix-faq.xml
similarity index 100%
rename from doc/appendix-faq.sgml
rename to doc/appendix-faq.xml
diff --git a/doc/appendix-packages.sgml b/doc/appendix-packages.xml
similarity index 100%
rename from doc/appendix-packages.sgml
rename to doc/appendix-packages.xml
diff --git a/doc/appendix-release-notes.sgml b/doc/appendix-release-notes.xml
similarity index 100%
rename from doc/appendix-release-notes.sgml
rename to doc/appendix-release-notes.xml
diff --git a/doc/appendix-signatures.sgml b/doc/appendix-signatures.xml
similarity index 100%
rename from doc/appendix-signatures.sgml
rename to doc/appendix-signatures.xml
diff --git a/doc/appendix-support.sgml b/doc/appendix-support.xml
similarity index 100%
rename from doc/appendix-support.sgml
rename to doc/appendix-support.xml
diff --git a/doc/cloning-standbys.sgml b/doc/cloning-standbys.xml
similarity index 100%
rename from doc/cloning-standbys.sgml
rename to doc/cloning-standbys.xml
diff --git a/doc/configuration-file-log-settings.sgml b/doc/configuration-file-log-settings.xml
similarity index 100%
rename from doc/configuration-file-log-settings.sgml
rename to doc/configuration-file-log-settings.xml
diff --git a/doc/configuration-file-required-settings.sgml b/doc/configuration-file-required-settings.xml
similarity index 100%
rename from doc/configuration-file-required-settings.sgml
rename to doc/configuration-file-required-settings.xml
diff --git a/doc/configuration-file-service-commands.sgml b/doc/configuration-file-service-commands.xml
similarity index 100%
rename from doc/configuration-file-service-commands.sgml
rename to doc/configuration-file-service-commands.xml
diff --git a/doc/configuration-file.sgml b/doc/configuration-file.xml
similarity index 100%
rename from doc/configuration-file.sgml
rename to doc/configuration-file.xml
diff --git a/doc/configuration.sgml b/doc/configuration.xml
similarity index 100%
rename from doc/configuration.sgml
rename to doc/configuration.xml
diff --git a/doc/event-notifications.sgml b/doc/event-notifications.xml
similarity index 100%
rename from doc/event-notifications.sgml
rename to doc/event-notifications.xml
diff --git a/doc/filelist.sgml b/doc/filelist.sgml
deleted file mode 100644
index 792ef61f..00000000
--- a/doc/filelist.sgml
+++ /dev/null
@@ -1,90 +0,0 @@
-<!-- doc/filelist.sgml -->
-
-<!ENTITY legal      SYSTEM "legal.sgml">
-
-<!ENTITY bookindex  SYSTEM "bookindex.sgml">
-
-<!--
- Some parts of the documentation are also source for some plain-text
- files used during installation.  To selectively ignore or include
- some parts (e.g., external xref's) when generating these files we use
- these parameter entities.  See also standalone-install.sgml.
- -->
-<!ENTITY % standalone-ignore  "INCLUDE">
-<!ENTITY % standalone-include "IGNORE">
-
-<!-- doc/filelist.sgml -->
-
-<!--
- By default, no index is included.  Use -i include-index on the command line
- to include it.
- -->
-<!ENTITY % include-index "IGNORE">
-
-<!--
- Create empty index element for processing by XSLT stylesheet.
- -->
-<!ENTITY % include-xslt-index "IGNORE">
-
-<!--
- Include external documentation sections
- -->
-
-<!ENTITY overview      SYSTEM "overview.sgml">
-<!ENTITY install SYSTEM "install.sgml">
-<!ENTITY install-requirements      SYSTEM "install-requirements.sgml">
-<!ENTITY install-packages      SYSTEM "install-packages.sgml">
-<!ENTITY install-source      SYSTEM "install-source.sgml">
-<!ENTITY quickstart      SYSTEM "quickstart.sgml">
-<!ENTITY configuration      SYSTEM "configuration.sgml">
-<!ENTITY configuration-file      SYSTEM "configuration-file.sgml">
-<!ENTITY configuration-file-required-settings      SYSTEM "configuration-file-required-settings.sgml">
-<!ENTITY configuration-file-log-settings      SYSTEM "configuration-file-log-settings.sgml">
-<!ENTITY configuration-file-service-commands   SYSTEM "configuration-file-service-commands.sgml">
-<!ENTITY cloning-standbys  SYSTEM "cloning-standbys.sgml">
-<!ENTITY promoting-standby  SYSTEM "promoting-standby.sgml">
-<!ENTITY follow-new-primary  SYSTEM "follow-new-primary.sgml">
-<!ENTITY switchover  SYSTEM "switchover.sgml">
-
-<!ENTITY event-notifications  SYSTEM "event-notifications.sgml">
-<!ENTITY upgrading-repmgr  SYSTEM "upgrading-repmgr.sgml">
-
-<!ENTITY repmgrd-overview SYSTEM "repmgrd-overview.sgml">
-<!ENTITY repmgrd-automatic-failover SYSTEM "repmgrd-automatic-failover.sgml">
-<!ENTITY repmgrd-configuration SYSTEM "repmgrd-configuration.sgml">
-<!ENTITY repmgrd-operation SYSTEM "repmgrd-operation.sgml">
-<!ENTITY repmgrd-bdr SYSTEM "repmgrd-bdr.sgml">
-
-<!ENTITY repmgr-primary-register SYSTEM "repmgr-primary-register.sgml">
-<!ENTITY repmgr-primary-unregister SYSTEM "repmgr-primary-unregister.sgml">
-<!ENTITY repmgr-standby-clone SYSTEM "repmgr-standby-clone.sgml">
-<!ENTITY repmgr-standby-register SYSTEM "repmgr-standby-register.sgml">
-<!ENTITY repmgr-standby-unregister SYSTEM "repmgr-standby-unregister.sgml">
-<!ENTITY repmgr-standby-promote SYSTEM "repmgr-standby-promote.sgml">
-<!ENTITY repmgr-standby-follow SYSTEM "repmgr-standby-follow.sgml">
-<!ENTITY repmgr-standby-switchover SYSTEM "repmgr-standby-switchover.sgml">
-<!ENTITY repmgr-witness-register SYSTEM "repmgr-witness-register.sgml">
-<!ENTITY repmgr-witness-unregister SYSTEM "repmgr-witness-unregister.sgml">
-<!ENTITY repmgr-node-status SYSTEM "repmgr-node-status.sgml">
-<!ENTITY repmgr-node-check SYSTEM "repmgr-node-check.sgml">
-<!ENTITY repmgr-node-rejoin SYSTEM "repmgr-node-rejoin.sgml">
-<!ENTITY repmgr-node-service SYSTEM "repmgr-node-service.sgml">
-<!ENTITY repmgr-cluster-show SYSTEM "repmgr-cluster-show.sgml">
-<!ENTITY repmgr-cluster-matrix SYSTEM "repmgr-cluster-matrix.sgml">
-<!ENTITY repmgr-cluster-crosscheck SYSTEM "repmgr-cluster-crosscheck.sgml">
-<!ENTITY repmgr-cluster-event SYSTEM "repmgr-cluster-event.sgml">
-<!ENTITY repmgr-cluster-cleanup SYSTEM "repmgr-cluster-cleanup.sgml">
-<!ENTITY repmgr-daemon-status SYSTEM "repmgr-daemon-status.sgml">
-<!ENTITY repmgr-daemon-start SYSTEM "repmgr-daemon-start.sgml">
-<!ENTITY repmgr-daemon-stop SYSTEM "repmgr-daemon-stop.sgml">
-<!ENTITY repmgr-daemon-pause SYSTEM "repmgr-daemon-pause.sgml">
-<!ENTITY repmgr-daemon-unpause SYSTEM "repmgr-daemon-unpause.sgml">
-
-<!ENTITY appendix-release-notes  SYSTEM "appendix-release-notes.sgml">
-<!ENTITY appendix-faq      SYSTEM "appendix-faq.sgml">
-<!ENTITY appendix-signatures      SYSTEM "appendix-signatures.sgml">
-<!ENTITY appendix-packages      SYSTEM "appendix-packages.sgml">
-<!ENTITY appendix-support SYSTEM "appendix-support.sgml">
-
-<!ENTITY bookindex  SYSTEM "bookindex.sgml">
-
diff --git a/doc/filelist.xml b/doc/filelist.xml
new file mode 100644
index 00000000..4cee5dc9
--- /dev/null
+++ b/doc/filelist.xml
@@ -0,0 +1,90 @@
+<!-- doc/filelist.xml -->
+
+<!ENTITY legal      SYSTEM "legal.xml">
+
+<!ENTITY bookindex  SYSTEM "bookindex.xml">
+
+<!--
+ Some parts of the documentation are also source for some plain-text
+ files used during installation.  To selectively ignore or include
+ some parts (e.g., external xref's) when generating these files we use
+ these parameter entities.  See also standalone-install.sgml.
+ -->
+<!ENTITY % standalone-ignore  "INCLUDE">
+<!ENTITY % standalone-include "IGNORE">
+
+<!-- doc/filelist.xml -->
+
+<!--
+ By default, no index is included.  Use -i include-index on the command line
+ to include it.
+ -->
+<!ENTITY % include-index "IGNORE">
+
+<!--
+ Create empty index element for processing by XSLT stylesheet.
+ -->
+<!ENTITY % include-xslt-index "IGNORE">
+
+<!--
+ Include external documentation sections
+ -->
+
+<!ENTITY overview      SYSTEM "overview.xml">
+<!ENTITY install SYSTEM "install.xml">
+<!ENTITY install-requirements      SYSTEM "install-requirements.xml">
+<!ENTITY install-packages      SYSTEM "install-packages.xml">
+<!ENTITY install-source      SYSTEM "install-source.xml">
+<!ENTITY quickstart      SYSTEM "quickstart.xml">
+<!ENTITY configuration      SYSTEM "configuration.xml">
+<!ENTITY configuration-file      SYSTEM "configuration-file.xml">
+<!ENTITY configuration-file-required-settings      SYSTEM "configuration-file-required-settings.xml">
+<!ENTITY configuration-file-log-settings      SYSTEM "configuration-file-log-settings.xml">
+<!ENTITY configuration-file-service-commands   SYSTEM "configuration-file-service-commands.xml">
+<!ENTITY cloning-standbys  SYSTEM "cloning-standbys.xml">
+<!ENTITY promoting-standby  SYSTEM "promoting-standby.xml">
+<!ENTITY follow-new-primary  SYSTEM "follow-new-primary.xml">
+<!ENTITY switchover  SYSTEM "switchover.xml">
+
+<!ENTITY event-notifications  SYSTEM "event-notifications.xml">
+<!ENTITY upgrading-repmgr  SYSTEM "upgrading-repmgr.xml">
+
+<!ENTITY repmgrd-overview SYSTEM "repmgrd-overview.xml">
+<!ENTITY repmgrd-automatic-failover SYSTEM "repmgrd-automatic-failover.xml">
+<!ENTITY repmgrd-configuration SYSTEM "repmgrd-configuration.xml">
+<!ENTITY repmgrd-operation SYSTEM "repmgrd-operation.xml">
+<!ENTITY repmgrd-bdr SYSTEM "repmgrd-bdr.xml">
+
+<!ENTITY repmgr-primary-register SYSTEM "repmgr-primary-register.xml">
+<!ENTITY repmgr-primary-unregister SYSTEM "repmgr-primary-unregister.xml">
+<!ENTITY repmgr-standby-clone SYSTEM "repmgr-standby-clone.xml">
+<!ENTITY repmgr-standby-register SYSTEM "repmgr-standby-register.xml">
+<!ENTITY repmgr-standby-unregister SYSTEM "repmgr-standby-unregister.xml">
+<!ENTITY repmgr-standby-promote SYSTEM "repmgr-standby-promote.xml">
+<!ENTITY repmgr-standby-follow SYSTEM "repmgr-standby-follow.xml">
+<!ENTITY repmgr-standby-switchover SYSTEM "repmgr-standby-switchover.xml">
+<!ENTITY repmgr-witness-register SYSTEM "repmgr-witness-register.xml">
+<!ENTITY repmgr-witness-unregister SYSTEM "repmgr-witness-unregister.xml">
+<!ENTITY repmgr-node-status SYSTEM "repmgr-node-status.xml">
+<!ENTITY repmgr-node-check SYSTEM "repmgr-node-check.xml">
+<!ENTITY repmgr-node-rejoin SYSTEM "repmgr-node-rejoin.xml">
+<!ENTITY repmgr-node-service SYSTEM "repmgr-node-service.xml">
+<!ENTITY repmgr-cluster-show SYSTEM "repmgr-cluster-show.xml">
+<!ENTITY repmgr-cluster-matrix SYSTEM "repmgr-cluster-matrix.xml">
+<!ENTITY repmgr-cluster-crosscheck SYSTEM "repmgr-cluster-crosscheck.xml">
+<!ENTITY repmgr-cluster-event SYSTEM "repmgr-cluster-event.xml">
+<!ENTITY repmgr-cluster-cleanup SYSTEM "repmgr-cluster-cleanup.xml">
+<!ENTITY repmgr-daemon-status SYSTEM "repmgr-daemon-status.xml">
+<!ENTITY repmgr-daemon-start SYSTEM "repmgr-daemon-start.xml">
+<!ENTITY repmgr-daemon-stop SYSTEM "repmgr-daemon-stop.xml">
+<!ENTITY repmgr-daemon-pause SYSTEM "repmgr-daemon-pause.xml">
+<!ENTITY repmgr-daemon-unpause SYSTEM "repmgr-daemon-unpause.xml">
+
+<!ENTITY appendix-release-notes  SYSTEM "appendix-release-notes.xml">
+<!ENTITY appendix-faq      SYSTEM "appendix-faq.xml">
+<!ENTITY appendix-signatures      SYSTEM "appendix-signatures.xml">
+<!ENTITY appendix-packages      SYSTEM "appendix-packages.xml">
+<!ENTITY appendix-support SYSTEM "appendix-support.xml">
+
+<!ENTITY bookindex  SYSTEM "bookindex.xml">
+
diff --git a/doc/follow-new-primary.sgml b/doc/follow-new-primary.xml
similarity index 100%
rename from doc/follow-new-primary.sgml
rename to doc/follow-new-primary.xml
diff --git a/doc/install-packages.sgml b/doc/install-packages.xml
similarity index 100%
rename from doc/install-packages.sgml
rename to doc/install-packages.xml
diff --git a/doc/install-requirements.sgml b/doc/install-requirements.xml
similarity index 100%
rename from doc/install-requirements.sgml
rename to doc/install-requirements.xml
diff --git a/doc/install-source.sgml b/doc/install-source.xml
similarity index 100%
rename from doc/install-source.sgml
rename to doc/install-source.xml
diff --git a/doc/install.sgml b/doc/install.xml
similarity index 100%
rename from doc/install.sgml
rename to doc/install.xml
diff --git a/doc/legal.sgml b/doc/legal.xml
similarity index 97%
rename from doc/legal.sgml
rename to doc/legal.xml
index 8c299132..fc04feec 100644
--- a/doc/legal.sgml
+++ b/doc/legal.xml
@@ -1,4 +1,4 @@
-<!-- doc/legal.sgml -->
+<!-- doc/legal.xml -->
 
 <date>2017</date>
 
diff --git a/doc/overview.sgml b/doc/overview.xml
similarity index 100%
rename from doc/overview.sgml
rename to doc/overview.xml
diff --git a/doc/promoting-standby.sgml b/doc/promoting-standby.xml
similarity index 100%
rename from doc/promoting-standby.sgml
rename to doc/promoting-standby.xml
diff --git a/doc/quickstart.sgml b/doc/quickstart.xml
similarity index 100%
rename from doc/quickstart.sgml
rename to doc/quickstart.xml
diff --git a/doc/repmgr-cluster-cleanup.sgml b/doc/repmgr-cluster-cleanup.xml
similarity index 100%
rename from doc/repmgr-cluster-cleanup.sgml
rename to doc/repmgr-cluster-cleanup.xml
diff --git a/doc/repmgr-cluster-crosscheck.sgml b/doc/repmgr-cluster-crosscheck.xml
similarity index 100%
rename from doc/repmgr-cluster-crosscheck.sgml
rename to doc/repmgr-cluster-crosscheck.xml
diff --git a/doc/repmgr-cluster-event.sgml b/doc/repmgr-cluster-event.xml
similarity index 100%
rename from doc/repmgr-cluster-event.sgml
rename to doc/repmgr-cluster-event.xml
diff --git a/doc/repmgr-cluster-matrix.sgml b/doc/repmgr-cluster-matrix.xml
similarity index 100%
rename from doc/repmgr-cluster-matrix.sgml
rename to doc/repmgr-cluster-matrix.xml
diff --git a/doc/repmgr-cluster-show.sgml b/doc/repmgr-cluster-show.xml
similarity index 100%
rename from doc/repmgr-cluster-show.sgml
rename to doc/repmgr-cluster-show.xml
diff --git a/doc/repmgr-daemon-pause.sgml b/doc/repmgr-daemon-pause.xml
similarity index 100%
rename from doc/repmgr-daemon-pause.sgml
rename to doc/repmgr-daemon-pause.xml
diff --git a/doc/repmgr-daemon-start.sgml b/doc/repmgr-daemon-start.xml
similarity index 100%
rename from doc/repmgr-daemon-start.sgml
rename to doc/repmgr-daemon-start.xml
diff --git a/doc/repmgr-daemon-status.sgml b/doc/repmgr-daemon-status.xml
similarity index 100%
rename from doc/repmgr-daemon-status.sgml
rename to doc/repmgr-daemon-status.xml
diff --git a/doc/repmgr-daemon-stop.sgml b/doc/repmgr-daemon-stop.xml
similarity index 100%
rename from doc/repmgr-daemon-stop.sgml
rename to doc/repmgr-daemon-stop.xml
diff --git a/doc/repmgr-daemon-unpause.sgml b/doc/repmgr-daemon-unpause.xml
similarity index 100%
rename from doc/repmgr-daemon-unpause.sgml
rename to doc/repmgr-daemon-unpause.xml
diff --git a/doc/repmgr-node-check.sgml b/doc/repmgr-node-check.xml
similarity index 100%
rename from doc/repmgr-node-check.sgml
rename to doc/repmgr-node-check.xml
diff --git a/doc/repmgr-node-rejoin.sgml b/doc/repmgr-node-rejoin.xml
similarity index 100%
rename from doc/repmgr-node-rejoin.sgml
rename to doc/repmgr-node-rejoin.xml
diff --git a/doc/repmgr-node-service.sgml b/doc/repmgr-node-service.xml
similarity index 100%
rename from doc/repmgr-node-service.sgml
rename to doc/repmgr-node-service.xml
diff --git a/doc/repmgr-node-status.sgml b/doc/repmgr-node-status.xml
similarity index 100%
rename from doc/repmgr-node-status.sgml
rename to doc/repmgr-node-status.xml
diff --git a/doc/repmgr-primary-register.sgml b/doc/repmgr-primary-register.xml
similarity index 100%
rename from doc/repmgr-primary-register.sgml
rename to doc/repmgr-primary-register.xml
diff --git a/doc/repmgr-primary-unregister.sgml b/doc/repmgr-primary-unregister.xml
similarity index 100%
rename from doc/repmgr-primary-unregister.sgml
rename to doc/repmgr-primary-unregister.xml
diff --git a/doc/repmgr-standby-clone.sgml b/doc/repmgr-standby-clone.xml
similarity index 100%
rename from doc/repmgr-standby-clone.sgml
rename to doc/repmgr-standby-clone.xml
diff --git a/doc/repmgr-standby-follow.sgml b/doc/repmgr-standby-follow.xml
similarity index 100%
rename from doc/repmgr-standby-follow.sgml
rename to doc/repmgr-standby-follow.xml
diff --git a/doc/repmgr-standby-promote.sgml b/doc/repmgr-standby-promote.xml
similarity index 100%
rename from doc/repmgr-standby-promote.sgml
rename to doc/repmgr-standby-promote.xml
diff --git a/doc/repmgr-standby-register.sgml b/doc/repmgr-standby-register.xml
similarity index 100%
rename from doc/repmgr-standby-register.sgml
rename to doc/repmgr-standby-register.xml
diff --git a/doc/repmgr-standby-switchover.sgml b/doc/repmgr-standby-switchover.xml
similarity index 100%
rename from doc/repmgr-standby-switchover.sgml
rename to doc/repmgr-standby-switchover.xml
diff --git a/doc/repmgr-standby-unregister.sgml b/doc/repmgr-standby-unregister.xml
similarity index 100%
rename from doc/repmgr-standby-unregister.sgml
rename to doc/repmgr-standby-unregister.xml
diff --git a/doc/repmgr-witness-register.sgml b/doc/repmgr-witness-register.xml
similarity index 100%
rename from doc/repmgr-witness-register.sgml
rename to doc/repmgr-witness-register.xml
diff --git a/doc/repmgr-witness-unregister.sgml b/doc/repmgr-witness-unregister.xml
similarity index 100%
rename from doc/repmgr-witness-unregister.sgml
rename to doc/repmgr-witness-unregister.xml
diff --git a/doc/repmgr.sgml b/doc/repmgr.xml
similarity index 96%
rename from doc/repmgr.sgml
rename to doc/repmgr.xml
index 43763016..aa660557 100644
--- a/doc/repmgr.sgml
+++ b/doc/repmgr.xml
@@ -1,12 +1,12 @@
-<!-- doc/repmgr.sgml -->
+<!-- doc/repmgr.xml -->
 
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
           "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
 [
-          <!ENTITY % version SYSTEM "version.sgml">
+          <!ENTITY % version SYSTEM "version.xml">
           %version;
 
-          <!ENTITY % filelist SYSTEM "filelist.sgml">
+          <!ENTITY % filelist SYSTEM "filelist.xml">
           %filelist;
 
           <!ENTITY repmgr "<productname>repmgr</productname>">
diff --git a/doc/repmgrd-automatic-failover.sgml b/doc/repmgrd-automatic-failover.xml
similarity index 100%
rename from doc/repmgrd-automatic-failover.sgml
rename to doc/repmgrd-automatic-failover.xml
diff --git a/doc/repmgrd-bdr.sgml b/doc/repmgrd-bdr.xml
similarity index 100%
rename from doc/repmgrd-bdr.sgml
rename to doc/repmgrd-bdr.xml
diff --git a/doc/repmgrd-configuration.sgml b/doc/repmgrd-configuration.xml
similarity index 100%
rename from doc/repmgrd-configuration.sgml
rename to doc/repmgrd-configuration.xml
diff --git a/doc/repmgrd-operation.sgml b/doc/repmgrd-operation.xml
similarity index 100%
rename from doc/repmgrd-operation.sgml
rename to doc/repmgrd-operation.xml
diff --git a/doc/repmgrd-overview.sgml b/doc/repmgrd-overview.xml
similarity index 100%
rename from doc/repmgrd-overview.sgml
rename to doc/repmgrd-overview.xml
diff --git a/doc/switchover.sgml b/doc/switchover.xml
similarity index 100%
rename from doc/switchover.sgml
rename to doc/switchover.xml
diff --git a/doc/upgrading-repmgr.sgml b/doc/upgrading-repmgr.xml
similarity index 100%
rename from doc/upgrading-repmgr.sgml
rename to doc/upgrading-repmgr.xml