The Vocabulary window is the Editor window that displays when its tab is the active window. A Vocabulary file has the extension .ecore. As the active window, the Vocabulary menu is available and the toolbar offers Vocabulary tools.

All elements of a Vocabulary are referred to generically as nodes, and these nodes are arranged in the Vocabulary window in a hierarchical, or “tree” view.

When a new Vocabulary is displayed in its window, the tree view is empty with the exception of the Vocabulary's “name” node. The name node contains the name of the Vocabulary and an “open book” icon to its left, as shown: