TTML1 3rd, TTML2, TTML-IMSC1 are W3C Recommendations
The Timed Text Working Group has published the following specifications as W3C Recommendations:
The Timed Text Markup Language is a content type that represents timed text media for the purpose of interchange among authoring systems. TTML Profiles are intended to be used across subtitle and caption delivery applications worldwide, thereby simplifying interoperability, consistent rendering and conversion to other subtitling and captioning formats.
