ensure that all docs use all entities files

Not all are needed for all files at the moment, but the new docbook
building hadn't available some of the entities it used as the files
weren't correctly copied around in all cases and having the same across
the bord makes working with all of them a little easier.

Git-Dch: Ignore

23 files changed, 75 insertions, 133 deletions

diff --git a/buildlib/docbook.mak b/buildlib/docbook.mak
index 272475721..6aa3ca0d2 100644
--- a/buildlib/docbook.mak
+++ b/buildlib/docbook.mak
@@ -13,6 +13,7 @@
 LOCAL := docbook-$(firstword $(SOURCE))
 $(LOCAL)-HTML := $(addsuffix .html,$(addprefix $(DOC)/,$(basename $(SOURCE))))
 $(LOCAL)-TEXT := $(addsuffix .text,$(addprefix $(DOC)/,$(basename $(SOURCE))))
+INCLUDES = apt.ent apt-verbatim.ent apt-vendor.ent
 
 docbook:
 
@@ -30,7 +31,7 @@ veryclean: veryclean/html/$(LOCAL)
 
 vpath %.dbk $(SUBDIRS)
 vpath $(DOCBOOK_HTML_STYLESHEET) $(SUBDIRS)
-$(DOC)/%.html: %.dbk $(DOCBOOK_HTML_STYLESHEET)
+$(DOC)/%.html: %.dbk $(DOCBOOK_HTML_STYLESHEET) $(INCLUDES)
 	echo Creating html for $< to $@
 	-rm -rf $@
 	mkdir -p $@
@@ -59,7 +60,7 @@ veryclean: veryclean/text/$(LOCAL)
 
 vpath %.dbk $(SUBDIRS)
 vpath $(DOCBOOK_TEXT_STYLESHEET) $(SUBDIRS)
-$(DOC)/%.text: %.dbk $(DOCBOOK_TEXT_STYLESHEET)
+$(DOC)/%.text: %.dbk $(DOCBOOK_TEXT_STYLESHEET) $(INCLUDES)
 	echo Creating text for $< to $@
 	$(DOCBOOK) \
 		--stringparam l10n.gentext.default.language $(LC) \
diff --git a/doc/apt-cache.8.xml b/doc/apt-cache.8.xml
index a53a64446..a9f6c8da2 100644
--- a/doc/apt-cache.8.xml
+++ b/doc/apt-cache.8.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-cdrom.8.xml b/doc/apt-cdrom.8.xml
index 2fcd8e494..23b26adaf 100644
--- a/doc/apt-cdrom.8.xml
+++ b/doc/apt-cdrom.8.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-config.8.xml b/doc/apt-config.8.xml
index b84d25f7a..f35f2488c 100644
--- a/doc/apt-config.8.xml
+++ b/doc/apt-config.8.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-extracttemplates.1.xml b/doc/apt-extracttemplates.1.xml
index 9f9888069..4a1f7213a 100644
--- a/doc/apt-extracttemplates.1.xml
+++ b/doc/apt-extracttemplates.1.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-ftparchive.1.xml b/doc/apt-ftparchive.1.xml
index 6482b4632..92016298d 100644
--- a/doc/apt-ftparchive.1.xml
+++ b/doc/apt-ftparchive.1.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-get.8.xml b/doc/apt-get.8.xml
index a3bfc331c..80b3be639 100644
--- a/doc/apt-get.8.xml
+++ b/doc/apt-get.8.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-key.8.xml b/doc/apt-key.8.xml
index 5dbbaaf26..1d91790ea 100644
--- a/doc/apt-key.8.xml
+++ b/doc/apt-key.8.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-mark.8.xml b/doc/apt-mark.8.xml
index d00e5b9e2..94f24437e 100644
--- a/doc/apt-mark.8.xml
+++ b/doc/apt-mark.8.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-secure.8.xml b/doc/apt-secure.8.xml
index 15a73476d..e343b86ea 100644
--- a/doc/apt-secure.8.xml
+++ b/doc/apt-secure.8.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt-sortpkgs.1.xml b/doc/apt-sortpkgs.1.xml
index 9bb03d624..c1f327fe8 100644
--- a/doc/apt-sortpkgs.1.xml
+++ b/doc/apt-sortpkgs.1.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt.8.xml b/doc/apt.8.xml
index 08a65ade2..29bf96751 100644
--- a/doc/apt.8.xml
+++ b/doc/apt.8.xml
@@ -1,13 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt.conf.5.xml b/doc/apt.conf.5.xml
index ffecc6ceb..df6c77ff0 100644
--- a/doc/apt.conf.5.xml
+++ b/doc/apt.conf.5.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/apt_preferences.5.xml b/doc/apt_preferences.5.xml
index d8c3efab7..16e6a7aa0 100644
--- a/doc/apt_preferences.5.xml
+++ b/doc/apt_preferences.5.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/doc/design.dbk b/doc/design.dbk
index 06743c8af..157e75c1a 100644
--- a/doc/design.dbk
+++ b/doc/design.dbk
@@ -1,8 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- -*- DocBook -*- -->
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <book lang="en">
diff --git a/doc/dpkg-tech.dbk b/doc/dpkg-tech.dbk
index e7d150cee..660ccabc9 100644
--- a/doc/dpkg-tech.dbk
+++ b/doc/dpkg-tech.dbk
@@ -1,8 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- -*- DocBook -*- -->
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <book lang="en">
diff --git a/doc/files.dbk b/doc/files.dbk
index 675c92664..f513e0008 100644
--- a/doc/files.dbk
+++ b/doc/files.dbk
@@ -1,8 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- -*- DocBook -*- -->
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <book lang="en">
diff --git a/doc/guide.dbk b/doc/guide.dbk
index e8a8ae274..80937164e 100644
--- a/doc/guide.dbk
+++ b/doc/guide.dbk
@@ -1,8 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- -*- DocBook -*- -->
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <book lang="en">
diff --git a/doc/makefile b/doc/makefile
index 5ab31ad3b..1c076d5be 100644
--- a/doc/makefile
+++ b/doc/makefile
@@ -29,7 +29,7 @@ include $(COPY_H)
 clean: clean/subdirs clean/examples
 veryclean: veryclean/subdirs clean/examples
 manpages: apt-vendor.ent manpages/subdirs
-docbook: docbook/subdirs
+docbook: apt-vendor.ent docbook/subdirs
 
 DOCUMENTATIONPO = $(patsubst %.po,%,$(notdir $(wildcard po/*.po)))
 DOCDIRLIST = $(addsuffix /makefile,$(DOCUMENTATIONPO))
diff --git a/doc/method.dbk b/doc/method.dbk
index d2eb04df1..09ef63e8c 100644
--- a/doc/method.dbk
+++ b/doc/method.dbk
@@ -1,8 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- -*- DocBook -*- -->
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <book lang="en">
diff --git a/doc/offline.dbk b/doc/offline.dbk
index 7163f8bd5..cbfc4f690 100644
--- a/doc/offline.dbk
+++ b/doc/offline.dbk
@@ -1,8 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- -*- DocBook -*- -->
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <book lang="en">
diff --git a/doc/sources.list.5.xml b/doc/sources.list.5.xml
index 4d0c4d502..da4f571b5 100644
--- a/doc/sources.list.5.xml
+++ b/doc/sources.list.5.xml
@@ -1,15 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
-<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
-%aptverbatiment;
-
-<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
-%aptvendor;
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
diff --git a/prepare-release b/prepare-release
index 0b7acc165..1b8f1e49e 100755
--- a/prepare-release
+++ b/prepare-release
@@ -69,6 +69,23 @@ elif [ "$1" = 'post-build' ]; then
 
 	dpkg-checkbuilddeps -d 'libxml2-utils'
 
+	HEADERBLUEPRINT="$(mktemp)"
+	sed -n '1,/^$/p' doc/apt.8.xml > "$HEADERBLUEPRINT"
+	find doc -mindepth 1 -maxdepth 1 -type f -name '*.xml' | while read FILE; do
+		if ! sed -n '1,/^$/p' "$FILE" | cmp "$HEADERBLUEPRINT" - >/dev/null 2>&1; then
+			echo >&2 "WARNING: Manpage $FILE has not the usual header! (see diff below)"
+			sed -n '1,/^$/p' "$FILE" | diff -u "$HEADERBLUEPRINT" - || true
+		fi
+	done
+	sed -n '1,/^$/p' doc/guide.dbk > "$HEADERBLUEPRINT"
+	find doc -mindepth 1 -maxdepth 1 -type f -name '*.dbk' | while read FILE; do
+		if ! sed -n '1,/^$/p' "$FILE" | cmp "$HEADERBLUEPRINT" - >/dev/null 2>&1; then
+			echo >&2 "WARNING: Documentation $FILE has not the usual header (see diff below)!"
+			sed -n '1,/^$/p' "$FILE" | diff -u "$HEADERBLUEPRINT" - || true
+		fi
+	done
+	rm "$HEADERBLUEPRINT"
+
 	# check the manpages with each vendor for vendor-specific errors…
 	find vendor -mindepth 1 -maxdepth 1 -type d | cut -d'/' -f 2 | while read DISTRO; do
 		ln -sf ../vendor/${DISTRO}/apt-vendor.ent doc