[DefaultValue(0)] public float BreadthLimit {get; set;}
[DefaultValue(0)] public float BreadthLimit {get; set;}
This property is just a suggested constraint on how broadly the tree will be laid out. When there isn't enough breadth for all of the children of a node, the children are placed in as many rows as needed to try to stay within the given breadth limit. If the value is too small, since this layout algorithm does not modify the size or shape of any node, the nodes will just be laid out in a line, one per row, and the breadth is determined by the broadest node. The distance between rows is specified by RowSpacing. To make room for the links that go around earlier rows to get to later rows, when the alignment is not a "center" alignment, the RowIndent property specifies that space at the start of each row.
This just gets or sets the RootDefaults's property of the same name.