Alright, I'm not really trying to get people to help me migrate away from OmniOutliner, so keep reading. What I'm actually trying to do is make a better case for using it. If I can find something running on Linux that can read OmniOutliner files, I'll be much more likely to rely on OmniOutliner on my Macs.

I know that OmniOutliner can export to OPML and that tons of stuff can read that. That's pretty lossy and anyway, OPML is a nasty format. What I want to know is whether I'm likely to find anything that runs on Linux that can read OmniOutliner files.

003 files are (optionally gzipped) XML, and there is a published DTD for them, so given standard XML utilities it is not too difficult to draft something that will read/write the format.