PDF docs from Org-mode: not valid PDF?

[Michael Hannon <jm_hannon@yahoo.com>]

Greetings.  The woman that runs our research group complains that she is
unable to print PDF documents that a couple of us in the group send her, and
that the two of us are the only source of such troublesome documents.

It occurred to me that the two of us are the only ones in the group that use
Emacs Org-mode to produce PDF documents.

I know there are web sites that can validate (i.e., measure conformance to the
standard of) HTML documents.  I wondered if there might be something similar
for PDF documents.

I found the following site:

    http://www.validatepdfa.com/

I don't much about the PDF standard, and I don't know anything about the
reliability of this site, but I've found that PDF documents that I generate
using Org-mode and send to that site come back with a boatload of validation
errors.

I've appended a sample Org-mode file that generates errors when I try to
validate it.  I've appended details of my configuration below the sample file.

I should mention that I have no trouble viewing the PDF file (using "evince"
on my Fedora system) or printing this file (to a Brother b/w printer).  Ditto for
my colleague on a MacOS X system.  Hence, I personally have no reason to
complain.  But there's that nagging issue with the boss.

Can anybody comment as to what I should expect in the way of validation?
And/or are there any settings that would affect this behavior?  I.e.,
something like:

    (setq org-export-pdf-use-strict t)

Thanks.

-- Mike

###### Beginning of sample Org-mode file
#+PROPERTY: session *R*
#+PROPERTY: cache yes
#+PROPERTY: results output verbatim
#+PROPERTY: tangle yes


* This is a test

#+BEGIN_SRC R :exports both
  
  x <- 7.2
  y <- 3
  
  print(x * y)
  
  
#+END_SRC

#+RESULTS:
: 21.6
###### End of sample Org-mode file

Emacs  : GNU Emacs 24.1.1 (x86_64-redhat-linux-gnu, GTK+ Version 2.24.13)
 of 2012-11-17 on buildvm-30.phx2.fedoraproject.org
Package: Org-mode version 7.9.2 (release_7.9.2-656-g2f9dda @
/usr/local/emacs.d/org-mode/org-devel/org-mode/lisp/)

current state:
==============
(setq
 org-export-preprocess-before-selecting-backend-code-hook
'(org-beamer-select-beamer-code)
 org-tab-first-hook '(org-hide-block-toggle-maybe
              org-src-native-tab-command-maybe
              org-babel-hide-result-toggle-maybe
              org-babel-header-arg-expand)
 org-speed-command-hook '(org-speed-command-default-hook
              org-babel-speed-command-hook)
 org-export-html-after-blockquotes-hook
'(org-special-blocks-convert-html-special-cookies)
 org-occur-hook '(org-first-headline-recenter)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-export-preprocess-before-normalizing-links-hook
'(org-remove-file-link-modifiers)
 org-confirm-shell-link-function 'yes-or-no-p
 org-export-latex-after-blockquotes-hook
'(org-special-blocks-convert-latex-special-cookies)
 org-export-latex-final-hook '(org-beamer-amend-header org-beamer-fix-toc
                   org-beamer-auto-fragile-frames
                   org-beamer-place-default-actions-for-lists)
 org-export-latex-after-initial-vars-hook '(org-beamer-after-initial-vars)
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-from-is-user-regexp "\\<Michael Hannon\\>"
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
             org-src-mode-configure-edit-buffer)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-mode-hook '(#[nil "\300\301\302\303\304$\207"
           [org-add-hook change-major-mode-hook org-show-block-all
            append local]
           5]
         #[nil "\300\301\302\303\304$\207"
           [org-add-hook change-major-mode-hook
            org-babel-show-result-all append local]
           5]
         org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point
              org-babel-execute-safely-maybe)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
          org-cycle-hide-inline-tasks org-cycle-show-empty-lines
          org-optimize-window-after-visibility-change)
 org-export-latex-format-toc-function 'org-export-latex-format-toc-default
 org-export-first-hook '(org-beamer-initialize-open-trackers)
 org-babel-tangle-lang-exts '(("C++" . "cpp") ("latex" . "tex")
                  ("python" . "py") ("lisp" . "lisp")
                  ("emacs-lisp" . "el"))
 org-confirm-elisp-link-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-structure-template-alist '(("r" "#+begin_src R\n\n#+end_src"
                 "<src lang=\"R\">\n\n</src>")
                ("S" "#+BEGIN_SRC ?\n\n#+END_SRC"
                 "<src lang=\"?\">\n\n</src>")
                ("s" "#+BEGIN_SRC ?\n\n#+END_SRC"
                 "<src lang=\"?\">\n\n</src>")
                ("e" "#+BEGIN_EXAMPLE\n?\n#+END_EXAMPLE"
                 "<example>\n?\n</example>")
                ("q" "#+BEGIN_QUOTE\n?\n#+END_QUOTE"
                 "<quote>\n?\n</quote>")
                ("v" "#+BEGIN_VERSE\n?\n#+END_VERSE"
                 "<verse>\n?\n</verse>")
                ("c" "#+BEGIN_CENTER\n?\n#+END_CENTER"
                 "<center>\n?\n</center>")
                ("l" "#+BEGIN_LaTeX\n?\n#+END_LaTeX"
                 "<literal style=\"latex\">\n?\n</literal>")
                ("L" "#+LaTeX: "
                 "<literal style=\"latex\">?</literal>")
                ("h" "#+BEGIN_HTML\n?\n#+END_HTML"
                 "<literal style=\"html\">\n?\n</literal>")
                ("H" "#+HTML: "
                 "<literal style=\"html\">?</literal>")
                ("a" "#+BEGIN_ASCII\n?\n#+END_ASCII")
                ("A" "#+ASCII: ")
                ("i" "#+INDEX: ?" "#+INDEX: ?")
                ("I" "#+INCLUDE: %file ?"
                 "<include file=%file markup=\"?\">")
                )
 org-babel-load-languages '((emacs-lisp . t) (lisp . t) (gnuplot . t) (R . t)
                (dot . t) (python . t) (sh . t) (latex . t)
                (C . t) (octave \.t))
 org-agenda-files '("~/Documents/scratch.org")
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 org-confirm-babel-evaluate 'my-org-confirm-babel-evaluate
 org-export-preprocess-after-blockquote-hook
'(org-special-blocks-make-special-cookies)
 org-src-fontify-natively t
 )