A dendrogram is a diagram used to show the hierarchical relationships between clusters, or words in the case of the UAT. This interactive dendrogram allows you to click on nodes to either expand or collapse the terms. When you expand a term you are able to explore that term’s child terms.
This dendrogram would not be possible without help from Alex Holachek, Metadata Specialist at SAO/NASA Astrophysics Data System, who wrote a Python script which transformed a flat XML file of the UAT into nested json. It also would not be possible without the D3.js library and Mike Bostock‘s dendrogram examples and code.