Now I'm not sure I know what you mean by 'nested tags'. What I am looking for is a way to organise my thoughts at the level of tags. e.g. suppose I were planning a trip with stops in 10 cities but haven't decided the order in which I would visit them. Notes with sites, restaurants, hotels, etc would be tagged with the relevant city. Then, once an itinerary is set, I list the tags in the correct order and the notes follow along. (it would be particularly nice if I could click on the tag and toggle the note view). In fact my purpose is more complex but this would be a simple example.