Color fidelity during transcoding

Hello public-tt,

 I'm pleased to note that all colors are specified in the sRGB color space.

Does TT AF DFXP express any conformance requirement regarding the
fidelity of the colors when converting to and from DFXP? I am thinking
not only of chrominance and white-point adaptation effects - which
should be minimal for modern equipment given that sRGB uses the 709
phosphor chromaticities - but more for differing assumptions on headroom
footroom, allowed colors, and corrections for flare, scene brightness,
surround and other viewing condition effects.

There is a useful discussion at
http://www.srgb.com/srgb709compatibility.html
How are sRGB and ITU-R BT.709-2 compatible?

Basically I am wondering how much guidance should be given in this area
such that reliable interchange between differing systems can be
achieved.

-- 
 Chris Lilley                    mailto:chris@w3.org
 Interaction Domain Leader
 Co-Chair, W3C SVG Working Group
 W3C Graphics Activity Lead
 Co-Chair, W3C Hypertext CG