Organizational Unit Types are the terms used to refer to levels in the hierarchy of your library system(s). Examples could include All-Encompassing Consortium, Consortium Within a Consortium, Library System, Branch, Bookmobile, Sub-Branch, Twig, etc.
You can add or remove organizational unit types, and rename them as needed to match the organizational hierarchy that exists in reality for the libraries using your installation of Evergreen. Evergreen can support organizations as simple as a single library with one or more branches or as complex as a consortium composed of many independently governed library systems.
If you have not already done so, please see Organization and Policy Editing for general information on changing policies within Evergreen.
To begin setting up your hierarchy, start at http://your.domain.com/cgi-bin/config.cgi and click on "Organizational Unit Types." You will be taken to the page shown on the right where you can add to, remove from, or reorganize the hierarchy as needed.