What are taxonomies?

A taxonomy is an abstract structure that contains a classification of terms. Taxonomies try to represent relations of things without going into more detail about the specific relations between these things (differentiation to ontology).
The term is derived from táxis and nomos, which means law of order.

In the literature taxonomies are always structured as follows:
There is always exactly ONE root, the top level of the taxonomy.
From this, so-called child terms (or child concepts) are derived, which in turn can have their own child concepts. Accordingly, the higher level term is called parent term (or parent concept). Concept and Term are to be used synonymously. (german: Konzept / Begriff)

Taxonomies in ILIAS

ILIAS already supports taxonomies in categories, question pools and glossaries. You can use so-called "nodes" at the same and on lower levels. You can use these nodes to filter the objects (or questions or items).

However the usabilty of taxonomies (especially in categories) is not very user-friendly. Users have to open alot of different tabs and they have to know where to find the different functions (p.e. nested nodes) to set taxonomies and nodes. Furthermore the usage of taxonomies from a user point of view is worthy of improvement, as it's not intuitive at the moment.

Where to find and set up Taxonomies:

• Categories: Metadata - Taxonomy Definition AND Metadata - Taxonomy Settings
• Glossaries: Settings - Taxonomy
• Question Pools: Settings - Taxonomies

Enabling of Taxonomies:

• Categories: Settings: "Taxonomies" (without a subline/explanation)
• Glossaries: Settings: "Show Taxonomy"
• Question Pools: Settings: "Show Taxonomies" (plus function: taxonomies as navigation tree)

Where to use Taxonomies:

• Categories: displayed in side block (if activated (Settings) AND manually shown (Metadata - Taxonomy Settings))
• Glossaries: displayed in main menu slate (if activated (Settings))
• Question Pools: displayed in inner content on the left side (if activated and used as Navigation Tree (Settings)) OR in filter (if activated (Settings))

Behavior of Taxonomies:

• Categories:
  • more than one taxonomy can be used in this context
  • click on node opens a new filtered category page (without page content)
  • click on more than one node opens all objects that are assigned to at least one of the marked nodes (NOT summed up)
  • click again on node deselects node
  • deselect all nodes DOESN'T lead back to category. You kind of get lost in an empty page. (Bug)
  • using "back" button DOESN'T deselect the nodes. You have to deselect first and click on back afterwards (Bug: https://mantis.ilias.de/view.php?id=31746)
• Glossaries: 
  • only one taxonomy can be used in this context
  • click on node filters Glossary: only assigned items are shown
  • click again on node DOESN'T deselect node
  • click on taxonomy (on top) to "deselect" nodes
• Question Pools: 
  • more than one taxonomy can be used but only one taxonomy can be used as navigation tree
  • click on node filters Question Pool: only assigned items are shown
  • click again on node DOESN'T deselect node
  • click on taxonomy (on top) to "deselect" nodes

• adding taxonomies and nodes in categories is user-unfriendly
  • you have to open a lot of different tabs in a lot of different objects 
  • there is no place where you can edit them directly
  • its not obvious, that you can add sub-nodes in categories
  • the slate (with taxonomy tree) should be open per default while editing a node; it should be shown while adding a new node so that users know, in which level they are right now. Furthermore the dropdowns including new subnodes should be open per default. (NEW)
• you cannot add global taxonomies
• you cannot ex- or import taxonomies in categories
• you cannot add multilingual taxonomies
• you cannot use system generated taxonomies (p.e. Boolean - beholder has/has not put to favourites yet; beholder is/is not member,...)

• you have two comparable filter options in categories: Filter and Taxonomies
  • Taxonomies should be moved to the filter

• you kind of get lost after using a node in a Category
  • you have to deselect all nodes AND have to click on "back" (UX bug, see chapter 3)
  • it would be user-friendlier, if deselect all nodes would automatically lead you back to the category (not important after moving Taxonomies to the Filter)
• you cannot select multiple nodes to narrow down your search, it gets summed up 
• interaction with Filter and Taxonomies is confusing and not working correctly
• you cannot save your choice: save your selected nodes for next time would be helpful
• show content narrowed down by selected nodes in tile view, when tile view is enabled in category --> different presentation can confuse the user