- Categorization vs. Classification
- Sub-sets vs. Categories
- Google Hierarchical Tags
- Tags with Properties
- Namespaces with Tags
- Storing Hierarchical Tags (parent/child, “Tag/Tag/Tag”)
Resources
- http://stackoverflow.com/questions/6345380/best-way-to-store-hierarchical-tags
- http://ux.stackexchange.com/questions/11107/can-tags-have-hierarchy
On Hierarchical Tags