diff --git a/tldp/doctypes/docbook4xml.py b/tldp/doctypes/docbook4xml.py
index b9fc422..adbb8e5 100644
--- a/tldp/doctypes/docbook4xml.py
+++ b/tldp/doctypes/docbook4xml.py
@@ -1,8 +1,18 @@
 #! /usr/bin/python
 # -*- coding: utf8 -*-
 
-from ..utils import logger, which, firstfoundfile
-from .common import SignatureChecker
+from __future__ import absolute_import, division, print_function
+
+import os
+import stat
+from tempfile import NamedTemporaryFile as ntf
+
+from tldp.utils import logger, which, execute, firstfoundfile
+from tldp.utils import arg_isexecutable, isexecutable
+from tldp.utils import arg_isreadablefile, isreadablefile
+
+from tldp.doctypes.common import BaseDoctype, SignatureChecker
+
 
 def xslchunk_finder():
     l = ['/usr/share/xml/docbook/stylesheet/ldp/html/tldp-sections.xsl',
@@ -23,30 +33,30 @@ def xslprint_finder():
 
 
 def config_fragment(p):
-    p.add_argument('--docbook4xml-xslchunk', type=str,
+    p.add_argument('--docbook4xml-xslchunk', type=arg_isreadablefile,
                    default=xslchunk_finder(),
-                   help='full path to LDP HTML section chunker XSL [%(default)s]')
-    p.add_argument('--docbook4xml-xslsingle', type=str,
+                   help='full path to LDP HTML chunker XSL [%(default)s]')
+    p.add_argument('--docbook4xml-xslsingle', type=arg_isreadablefile,
                    default=xslsingle_finder(),
                    help='full path to LDP HTML single-page XSL [%(default)s]')
-    p.add_argument('--docbook4xml-xslprint', type=str,
+    p.add_argument('--docbook4xml-xslprint', type=arg_isreadablefile,
                    default=xslprint_finder(),
                    help='full path to LDP FO print XSL [%(default)s]')
-    p.add_argument('--docbook4xml-xsltproc', type=which,
+    p.add_argument('--docbook4xml-xsltproc', type=arg_isexecutable,
                    default=which('xsltproc'),
                    help='full path to xsltproc [%(default)s]')
-    p.add_argument('--docbook4xml-html2text', type=which,
+    p.add_argument('--docbook4xml-html2text', type=arg_isexecutable,
                    default=which('html2text'),
                    help='full path to html2text [%(default)s]')
-    p.add_argument('--docbook4xml-fop', type=which,
+    p.add_argument('--docbook4xml-fop', type=arg_isexecutable,
                    default=which('fop'),
                    help='full path to fop [%(default)s]')
-    p.add_argument('--docbook4xml-dblatex', type=which,
+    p.add_argument('--docbook4xml-dblatex', type=arg_isexecutable,
                    default=which('dblatex'),
                    help='full path to dblatex [%(default)s]')
 
 
-class Docbook4XML(SignatureChecker):
+class Docbook4XML(BaseDoctype, SignatureChecker):
     formatname = 'DocBook XML 4.x'
     extensions = ['.xml']
     signatures = ['-//OASIS//DTD DocBook XML V4.1.2//EN',
@@ -54,20 +64,96 @@ class Docbook4XML(SignatureChecker):
                   '-//OASIS//DTD DocBook XML V4.2//EN',
                   '-//OASIS//DTD DocBook XML V4.4//EN',
                   '-//OASIS//DTD DocBook XML V4.5//EN', ]
-    tools = ['xsltproc', 'html2text', 'fop', 'dblatex']
-    files = ['']
+    required = {'docbook4xml_xsltproc': isexecutable,
+                'docbook4xml_html2text': isexecutable,
+                'docbook4xml_dblatex': isexecutable,
+                'docbook4xml_fop': isexecutable,
+                'docbook4xml_xslchunk': isreadablefile,
+                'docbook4xml_xslsingle': isreadablefile,
+                'docbook4xml_xslprint': isreadablefile,
+                }
 
-    def create_txt(self):
-        logger.info("Creating txt for %s", self.source.stem)
+    buildorder = ['shellscript']
+    script = '''#! /bin/bash
+#
+# -- generate LDP outputs from DocBook XML 4.x
 
-    def create_pdf(self):
-        logger.info("Creating PDF for %s", self.source.stem)
+set -x
+set -e
+set -o pipefail
 
-    def create_html(self):
-        logger.info("Creating chunked HTML for %s", self.source.stem)
+cd "{output.dirname}"
+
+"{config.docbook4xml_xsltproc}" > "{output.name_htmls}" \\
+  --nonet \\
+  --stringparam admon.graphics.path images/ \\
+  --stringparam base.dir . \\
+  "{config.docbook4xml_xslsingle}" \\
+  "{source.filename}"
+
+"{config.docbook4xml_html2text}" > "{output.name_txt}" \\
+  -style pretty \\
+  -nobs \\
+  "{output.name_htmls}"
+
+"{config.docbook4xml_xsltproc}" > "{output.name_fo}" \\
+  "{config.docbook4xml_xslprint}" \\
+  "{source.filename}"
+
+"{config.docbook4xml_fop}" \\
+  -fo "{output.name_fo}" \\
+  -pdf "{output.name_pdf}" \\
+  && rm -f -- "{output.name_fo}"
+
+# "{config.docbook4xml_dblatex}" \\
+#   -F xml \\
+#   -t pdf \\
+#   -o "{output.name_pdf}" \\
+#      "{source.filename}"
+
+"{config.docbook4xml_xsltproc}" \\
+  --nonet \\
+  --stringparam admon.graphics.path images/ \\
+  --stringparam base.dir . \\
+  "{config.docbook4xml_xslchunk}" \\
+  "{source.filename}"
+
+mv \\
+  --no-clobber \\
+  --verbose \\
+  -- "{output.name_indexhtml}" "{output.name_html}"
+
+ln \\
+  --symbolic \\
+  --relative \\
+  --verbose \\
+  -- "{output.name_html}" "{output.name_indexhtml}"
+
+# -- end of file'''
+
+    def shellscript(self):
+        source = self.source
+        output = self.output
+        logdir = self.output.logdir
+        config = self.config
+
+        s = self.script.format(output=self.output,
+                               source=self.source,
+                               config=self.config)
+        tf = ntf(dir=self.output.logdir, prefix='docbook4xml-shell-', 
+                 suffix='.sh', delete=False)
+        tf.write(s)
+        tf.close()
+
+        mode = stat.S_IXUSR | stat.S_IRUSR | stat.S_IWUSR
+        os.chmod(tf.name, mode)
+
+        cmd = [tf.name]
+        result = execute(cmd, logdir=logdir)
+        if result != 0:
+            return False
+        return self.output.iscomplete
 
-    def create_htmls(self):
-        logger.info("Creating single page HTML for %s", self.source.stem)
 
 #
 # -- end of file