Only thing I would think of changing would be allowing for the use of colons in tags to provide tag namespaces. Then it's fairly trivial to implement things like created on date, completion date, and the like since it's just "#created-on:yyyy-mm-dd" or "#completed-on:yyyy-mm-dd".
It also allows users more generic organization options, with filtering based on the namespaced tags being something trivial, but ultimately up to the user or the app that is interfacing with the xit file.
It also allows users more generic organization options, with filtering based on the namespaced tags being something trivial, but ultimately up to the user or the app that is interfacing with the xit file.