On this type of diagram, symbols can be arranged into a tree for instance:
When a node being drawn or pasted can be attached to a tree, a + sign is shown within the region for the symbol:
As the symbol is moved beneath a potential parent, a tree anchorage indication appears. The symbol can be moved when you move the mouse cursor far enough away from this location. The plus indicator remains near the mouse cursor:
This indicates that the node will be inserted between two others:
If you release the mouse button then the tree is adjusted and you are prompted for the name if this is the action of creating a new symbol:
Pressing Escape to Cancel will remove the node and return the tree to the prior state.
If you drag a node that has children then the children will also be dragged:
Keyboard interface
The keyboard interface is slightly different on these diagrams.
Hold down Shift while using the cursor keys to move the cursor.
When a tree node has been selected, the cursor keys, without holding down Shift, will change the selected node:
•Left and right will change selection to the sibling that is next in position to the left and right, respectively.
•Up and down will change selection to the parent and subordinate respectively.
Representationally Consistent diagrams
Attaching a node to a parent adds a reference from the child node to the parent.
Cutting using Edit>Cut or Ctrl+X, or by dragging a node to detach it from a parent, removes a reference. Use a delete action and then select remove to remove a node without removing the reference.
Adding duplicate nodes will only move them into the tree where there is not a symbol representing the same definition already parented under that node.
