There used to be published and documented specs for the .WEB format on the xara.com site. I don't know if it's still there, norr how the WEB format differs from the XAR format - but it could be worth checking into, eh? I agree that full disclosure of the XAR format would be good!

K
www.xaraxone.com/FeaturedArt/kn/
www.klausnordby.com/xara