I'm not sure this is the best tool for an import-export format, as it is unable to capture all of the data available in some to do apps.
I could see it being OK as a sort-of data backup format. But it's missing a lot of data that really ought to be tracked by an app, like creation, update, and completion times for each item. Many apps also track priority, sort order, hidden/unhidden status, attachments, and other things. This stores none of that.
Even then, the value is fairly small. In 20+ years of using to do apps, I can think of very few times that I've referred back to completed to do items.
I could see it being OK as a sort-of data backup format. But it's missing a lot of data that really ought to be tracked by an app, like creation, update, and completion times for each item. Many apps also track priority, sort order, hidden/unhidden status, attachments, and other things. This stores none of that.
Even then, the value is fairly small. In 20+ years of using to do apps, I can think of very few times that I've referred back to completed to do items.