As linguistics and language documentation interface with digital humanities there has been a lot of effort to time-align texts and audio/video materials. At one level this is rather trivial to do and has the backing of comercial media processes like subtitles in movies. However, at another level this task is often done in XML for every project (digital corpus curation) slightly differently. At the macro-scale the argument is that if the annotation of the audio is in XML and someone wants to do something else with it, then they can just convert the XML to whatever schema they desire. This is true.
However, one antidotal point that I have not heard in discussion of time aligned texts is specifications for Audio Dominant Text vs. Text Dominant Audio. This may not initially seem very important, so let me explain what I mean.