[ttml2] Change "altitude" to "ascent".

skynavga has just created a new issue for https://github.com/w3c/ttml2:

== Change "altitude" to "ascent". ==
In line height text, change altitude to refer to ascent; also add note referring to OpenType realization.

Please view or discuss this issue at https://github.com/w3c/ttml2/issues/889 using your GitHub account

Received on Thursday, 12 July 2018 15:00:13 UTC