Index: /trunk/doc/manual/Makefile.kmk
===================================================================
--- /trunk/doc/manual/Makefile.kmk	(revision 56470)
+++ /trunk/doc/manual/Makefile.kmk	(revision 56471)
@@ -660,4 +660,17 @@
 	$(MAKE) --pretty-command-printing -j1 VBOX_PDFLATEX_INTERACTION=errorstopmode $(PATH_STAGE_BIN)/UserManual.pdf
 
+# validate each processed set of XML files
+define def_vbox_validate_xml
+validatemanual_$(lang): \
+$$(addprefix $(VBOX_PATH_MANUAL_OUTBASE)/$(lang)/,$(VBOX_MANUAL_XML_FILES_INCL_CHANGELOG)) \
+	$$(MAKEFILE_CURRENT)
+	$$(QUIET)xmllint --dtdvalid $$(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --xinclude --noout $$<
+endef
+
+$(foreach lang,$(VBOX_MANUAL_LANGUAGES),$(eval $(def_vbox_validate_xml)))
+
+# validate all translations of the manual
+validatemanual: $(foreach lang,$(VBOX_MANUAL_LANGUAGES),validatemanual_$(lang))
+
 
 #
@@ -700,4 +713,10 @@
 
 
+# validate SDK manual
+validatesdkref: $(addprefix $(VBOX_PATH_MANUAL_OUTBASE)/en_US/,$(VBOX_SDKREF_XML_FILES)) \
+	$(MAKEFILE_CURRENT)
+	$(QUIET)xmllint --dtdvalid $(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --xinclude --noout $<
+
+
 
 ifdef VBOX_WITH_DOCS_CHM
@@ -898,4 +917,9 @@
 $(evalcall2 def_vbox_replace_paths_in_xslt,docbook-refentry-to-C-help.xsl,)
 $(evalcall2 def_vbox_replace_paths_in_xslt,docbook-refentry-to-H-help.xsl,)
+
+# validate man page XML source
+validateman: $(addprefix $(VBOX_PATH_MANUAL_SRC)/en_US/,$(VBOX_MANUAL_XML_REFENTRY_FILES)) \
+	$(MAKEFILE_CURRENT)
+	$(QUIET)xmllint --dtdvalid $(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --noout $<