[imsc] No negative values for tts:disparity

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

== No negative values for tts:disparity ==
In TTML2, the [`tts:disparity` attribute](https://w3c.github.io/ttml2/#style-attribute-disparity) value is defined to be `<length>`. However IMSC 1.1 prohibits the feature `#length-negative` i.e. negative lengths. So there can be no content in front of the plane of display, as this would require a negative length value.

Is this intentional?

Please view or discuss this issue at https://github.com/w3c/imsc/issues/370 using your GitHub account

Received on Wednesday, 25 April 2018 15:26:22 UTC