diff -r 1ebcbfc71e2f a2x.py
--- a/a2x.py	Sun Feb 17 10:37:43 2013 +1300
+++ b/a2x.py	Wed Jul 03 11:28:03 2013 +1000
@@ -670,6 +670,7 @@
             self.exec_dblatex()
 
     def exec_fop(self):
+		self.asciidoc_opts += ' -a fop'
         self.to_docbook()
         docbook_file = self.dst_path('.xml')
         xsl = self.xsl_stylesheet('fo.xsl')
diff -r 1ebcbfc71e2f doc/a2x.1.txt
--- a/doc/a2x.1.txt	Sun Feb 17 10:37:43 2013 +1300
+++ b/doc/a2x.1.txt	Wed Jul 03 11:28:03 2013 +1000
@@ -121,7 +121,8 @@
 
 *--fop*::
   Use FOP to generate PDFs. The default behavior is to use
-  'dblatex(1)'.  The '--fop' option is implicit if this option is
+  'dblatex(1)'.  The Asciidoc 'fop' attribute is set if this option
+  is used.  The '--fop' option is implicit if this option is
   used.
 
 *--fop-opts*='FOP_OPTS'::