[imsc] Limit application of rw/rh tts:extent and tts:position

palemieux has just created a new issue for https://github.com/w3c/imsc:

== Limit application of rw/rh tts:extent and tts:position ==
When horizontal relative lengths (`rw`) are used in vertical extent or position dimensions, or conversely when vertical relative lengths (`rh`) are used in horizontal extent or position dimensions, the determination of whether the region extend beyond the root container becomes dependent on the aspect ratio of the root container, which is not always available to the author.

Suggest prohibiting the application of horizontal relative lengths in a vertical context, and vice versa, when applied to `tts:extent` and `tts:position`.

See also https://github.com/w3c/imsc-tests/issues/77#issuecomment-417373785

Please view or discuss this issue at https://github.com/w3c/imsc/issues/445 using your GitHub account

Received on Thursday, 30 August 2018 17:03:20 UTC