Tagcoll takes a collection of items categorized with multiple tags and performs various kinds of operations on them:

* organize the collection in an intuitively navigable hierarchy; * discover and show implicit hierarchical relationships between tags; * apply various transformations to the collection * produce a special patch file with the differencies between two collections. Such patch files are specific to tagged collections, and can be applied and merged more freely than normal diff output; * apply a previously generated patch file to a collection.

tagcoll has been written with the purpose of studying tagged collections and experiment with tagged collection algorithms.