: The easiest way I can think of to get that effect is to store all the : fields so you can re-create the Document and change the field being : updated.
My brief reading of hte GData URL Doug sent suggestes that the overall theme is content storage -- if that's the goal, mandating that "modify" operations require all fields be stored wouldn't sacrifice functionality. As far as the output format -- it seems to me that just like A9's OpenSearch this cold probably be done entirely with an XSLT. The input format is the trickier part .. that's where we'd definitely need a more pluggable "parser" for dealing with incoming data. ... but we're going to need that anyway if we want to support posting CSV files and things like that. -Hoss