Nicolas,

Thank you for the message. I spent about 2 hours on it today learning more about lisp and the internals to explain your email to me. I learned a lot.

I have modified ox-html.el to include a local OPTION as well as a customizable setting. I tested with both as well as with an export option. All three worked correctly. I also updated the org-manual.org.

Please find my patch attached.

Cheers,
Brian