Help - Changing a document element ID
From TreeGraph help
Labels can be grouped with an ID so that these groups can be selected and edited together easily. These IDs can be changed via the "Change ID"-dialog.
The dialog
You can access the "Change ID"-dialog by selecting a label and than choosing the "Change ID..."-option from the edit menu or the context menu.
In the dialog you can either choose any ID that is already assigned to a document element in the tree from the drop down list or enter a new ID.
