[O] Some commands are not exported to LaTeX

[Rafael]

With Emacs 23.3.1 in Ubuntu 11.10, and recent org (Org-mode version 7.7
(release_7.7.601.g55e4d), loaded after emacs -Q), consider the following
file. When exporting to LaTeX, the rows starting with #+attr_html,
#attr_latex, #+caption, do not appear. Both html and odt export are
fine.

#+TITLE: Hello, World

* An org mode code example

#+begin_src org
  ,#+title: Hello
  
  ,* This is an example
  
  ,#+attr_html: width="50%"
  ,#+attr_latex: height=0.5\textheight
  ,#+attr_odt: (:scale 0.5)
  ,#+caption: A caption
  ,[[file:figure.jpg]]
#+end_src