Prime Therapeutics has the following request for hierarchical tags in the content library.
From Prime: "All tags should display on a record, and in the proper parent, child, grandchild order. The design where only the lowest level tag displays but you can hover over it to see the tag stream isn’t very good. We want to put information in front of people, not make them look for it. Today, the tags might not be in a helpful order, but at least I can easily see them all."