At the risk of jumping ahead of Chris, I think Kris's description is better. But we still (IMO) must reference the HTML5 spec (WHATWG version), for this and likely for other multimedia element properties. Tabindex is at https://html.spec.whatwg.org/#the-tabindex-attribute.
I'll note that @tabindex doesn't really make sense for
<audio> and <video>.
Also, if I could wave a magic wand and specify these multimedia
properties as attributes, not elements, I would. I acknowledge
that this was necessary for 1.3 (because we can't define
element-specific attribute specializations), but we could consider
flipping these properties to attribute values for 2.0.
-Alan
Chris, would you please take a look at this thread in the DITAweb review? It concerns @tabindex on <audio>:
Here is the content of the draft comment:
--
Best,
Kris
Kristen James Eberlein
Chair, OASIS DITA Technical Committee
Principal consultant, Eberlein Consulting
www.eberleinconsulting.com
+1 919 622-1501; kriseberlein (skype)
-- Alan Houser Group Wellesley, Inc. Consultant and Trainer, Technical Publishing arh on Twitter 412-450-0532