Wow, this was fast.
As for the action model of SWF 10, there were no changes from SWF 9. Considering that SWF 9 action model consisted of the DoABC tag which contained AS3/ABC data, this is hardly surprising. As far as I can see, the PDF that described ABC internals hasn’t been updated yet.
[Update note: Original link to Emmy's post was http://weblogs.macromedia.com/emmy/archives/2008/11/swf_10_spec_available_and_flash_player_alpha_for_64-bit_linux_on_labs.html]