> ## Documentation Index > Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt > Use this file to discover all available pages before exploring further. # Classifier window > See how the Classifier window displays created classes and the classification tree, where each node is a stage you can move or copy in FlexiLayout Studio. Screenshot of the Classifier window showing the list of created classes and the classification structure as a tree-like diagram The **Classifier** window displays the list of created classes (the **Classes** group) and the classification structure as a tree-like diagram. The root folder of the tree represents the entire classifier. ## Classification tree structure Each node in the tree corresponds to a classification stage. A node contains a group identifier element (named **Id** by default) and nested nodes. The nesting depth is not limited. ## Move and copy classification stages You can rearrange stages directly in the tree using one of the following actions: * **Move** a stage by dragging and dropping it. * **Copy** a stage by holding **Ctrl** while you drag and drop it. ## Related topics * [Classification](/flexi-capture/fls/classification)