After I posted an iGTD to Omnifocus applescript (http://web.mac.com/robinfrancistrew/...OmniFocus.html),
I was asked, on the iGTD site, perhaps a little tetchily, whether I would now write an Omni to iGTD script.

I would personally welcome the emergence of a standard human-readable (XML) interchange format which would allow GTD data-stores to move fairly freely from one app to another, and allow for some easy sharing of project outlines etc.

A candidate format might be OPML. Projects, sub-projects and actions could be readily nested, while Contexts and other action fields could be encoded as attributes of project and action nodes. A distinct subtree could store a Context tree.

If I had the time I might re-write the iGTD importer so that it first exports from iGTD to a GTD OPML, and then imports to Omnifocus from that GTD OPML. It would then be easier to add importers and exporters for additional applications.

It would, of course, be ideal if a standardized GTD OPML were to emerge, allowing developers to build reading and writing routines into their applications ...