Usually the general element has more than one specific elements and sometimes specific elements may have their specific elements - the diagram with these generalizations may become messy. To display the generalization relationships and specific elements orderly, the generalization tree can be created.

To group generalization paths into a tree, do one of the following

• When drawing generalizations, connect each following generalization to the first one.
  
• If all generalizations are drawn separately, do on of the following:
  
  • Select the generalization and drag it to the other generalization.
    
    
    
  • Select the generalization element and from its shortcut menu select Refactor > Make Sub Tree.
    
    
    
  • Select all elements you want to add to the tree and, on the diagram toolbar, click the Quick Diagram Layout (Ctrl + Q) button and select one of the tree form layout.
    
    

To ungroup a generalization tree, do one of the following

• Right click any relationship in the generalization tree. On the opened shortcut menu, click Ungroup tree.
• Select the end of a concrete generalization relationship and drag it to other element.