RE: [Mediann] Ad. "Return Type / String vs Uri" - Issue

Hi all,
In order to facilitate the discussion on data interchange format, I have assembled the options on a wiki page:
http://www.w3.org/2008/WebVideo/Annotations/wiki/Dataformat

Personally I like the idea of JSONs collection of name/value pairs.
Some thoughts are:
1) Can we have two levels of complexity e.g. simple (string) and complex (e.g. collection of name/Value pairs) depending on property or application?
2) How does the application know what is returned?

/J