This document collects together into one place all the specifications (versions, profiles), as of 2014, produced by the Timed Text Working Group (TTWG) regarding the Timed Text Markup Language (TTML). The document is intended for TTML authors and TTML implementors to help them identifying which specification is relevant for their application.


The TTWG produces specifications for media online captioning, and in particular develops and maintains versions of the Timed Text Markup Language (TTML). Several versions of this language and several profiles have been produced. The purpose of this document is to collect all versions and profiles of the TTML language, as defined by the W3C. Extensions and other profiles of TTML may be defined by other entities and are not listed in this document.

TTML Versions

Timed Text Markup Language 1 (TTML1)

[[TTML10]] is the first version of the TTML language developped by the TTWG. The first edition was published in November 2010. Errata items were identified and integrated in a Second Edition in September 2013. The TTWG also produced profiles related to this specification (see next section). The TTWG will continue the development of this specification, possibly publishing new editions integrating new features or errata items.

Timed Text Markup Language 2 (TTML2)

[[TTML2]], currently at draft stage, represents a new version of the TTML language that is intended to co-exist with [[TTML10]].

TTML Profiles

TTML Simple Delivery Profile for Closed Captions (SPD-US)

The Simple Delivery Profile for Closed Captions is a TTWG Note whose goal is to establish a minimum level of interoperability between [[TTML10]] and legacy caption formats employed in US markets, such as [[CEA608] and [[CEA708].

TTML Text and Image Profiles for Internet Media Subtitles and Captions 1.0 (IMSC1)

IMSC1[[IMSC1]] specifies two profiles of [TTML1]: a text-only profile and an image-only profile. These 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. The text profile is a superset of [[SDPUS]].