I'm not sure any of this really addresses the question - which is how do people really use files. IME I have a number of live projects which can contain variou

I'm not sure any of this really addresses the question - which is how do people really use files. IME I have a number of live projects which can contain various numbers of source files, images, web links, PDFs and other documents, text files, and so on. Then there are a number of files I access regularly which may not be associated with a project (like favourite music). Then there's a mountain of data which is just there in case I ever need it. It includes backups of old projects, documents, music and art I keep because I think it's interesting but haven't read yet, web links that are filed and then (sadly...) forgotten, and so on. I don't know how typical this is, and it doesn't matter. Because neither a tag based nor a tree based system address the real issue - which is designing a custom file workflow that collects related references of all kinds, doesn't confuse working data with long-term storage, allows off-site backups, allows collaboration, supports versioning on demand, and also makes it easy to find things. I suppose all of that means some kind of process API which does a lot more than file.open() and file.close(). It could be built on tags, it could be built on trees, it could be built on some combination. Or on something else entirely. The implementation matters a lot less than a set of available features which streamline common tasks in some fairly standardised and effective way.