This section of the guide describes the that are likely to be required to navigate hierarchies.
One of the key strengths of rich set of that connect the within the terminology. The primary use of these is to facilitate selective retrieval. However, some of these are arranged in hierarchies that can be navigated using an appropriate user-interface control. For example, the formed by the can be used to navigate from a selected to another that has a more specific or less specific meaning.
also specifies standard ways to represent multiple hierarchies that can be designed to meet different requirement. Unlike based hierarchies, hierarchies convey no semantic information but are intended to be used to enhance the user experience when navigating through the terminology.