XML setting node type

I’m just trying out this plugin for the first time. When using XML to load the tree, how do you specify which items are leaf nodes and which are non-leaf(folder) nodes?

I am using the Inline XML loading method

Please, look through attentively xml files are placed in your suit: dhtmlxTree/samples/common/
An xml structure is build the next way:

The first 4 items are brunches, because have nesting.
The 5th one (id=“lb_1”) hasn’t any nesting, therefore it is a leaf.