[ttml2] Clarify behavior in case of error in the frame rate attribute (#1113)

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

== Clarify behavior in case of error in the frame rate attribute ==
Related to #1098 

Please view or discuss this issue at https://github.com/w3c/ttml2/issues/1113 using your GitHub account

Received on Thursday, 6 June 2019 15:51:52 UTC