The Taskpaper text format, which can be exported from, and imported into OmniFocus, is very easy to work with, and can be edited with various on-line and local tools including a Windows editor called TodoPaper.

I use it on Windows both for capturing projects and actions that come to mind, and for working through action lists. (Easily emailed to and from OS X, and extracted from, or absorbed into, OmniFocus, which is, of course, much more powerful for weekly or daily reviews).

The various Omni action fields (dates, done, duration etc) can be exported and imported as Taskpaper tags.

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