The W3C the Timed Text (TT) Working Group has posted the second public working draft of Timed Text (TT) Authoring Format 1.0 – Distribution Format Exchange Profile (DFXP). According to the abstract,
This document specifies the distribution format exchange profile (DFXP) of the timed text authoring format (TT AF) in terms of a vocabulary and semantics thereof.
The timed text authoring format is a content type that represents timed text media for the purpose of interchange among authoring systems. Timed text is textual information that is intrinsically or extrinsically associated with timing information.
The Distribution Format Exchange Profile is intended to be used for the purpose of transcoding or exchanging timed text information among legacy distribution content formats presently in use for subtitling and captioning functions.
In addition to being used for interchange among legacy distribution content formats, DFXP content may be used directly as a distribution format, providing, for example, a standard content format to reference from a
<text>or<textstream>media object element in a [SMIL2] document.