[ttml1] Pull Request: Clarified TAB character presentation semantics

palemieux has just submitted a new pull request for https://github.com/w3c/ttml1:

== Clarified TAB character presentation semantics ==
Closes #235

See https://github.com/w3c/ttml1/pull/258

Received on Tuesday, 14 November 2017 22:32:45 UTC