"Could the order of tags be a general solution for hierarchical tagging? It would be similar to relations between words within sentences or to the order of folders in a directory and without enforcing a structure."
DiskWarrior is the most highly decorated Mac disk repair utility ever. It repairs disks that no other program can repair. New hardware monitoring helps protect your data from drive malfunctions.
L. Heller, R. The, and S. Bartling. Opening Science: The Evolving Guide on How the Internet is Changing Research, Collaboration and Scholarly Publishing, Springer, Heidelberg and New York, (2014)