Specify whether the annotation text will be wrapped so as to maximally utilize the empty space arisen in the diagram because of its layout, thereby minimizing the bloating of the diagram by annotations themselves. This allows you to make the whole diagram more compact.
The optimization is focused on minimizing the annotation wrapping (i.e. maximizing the wrapping widths) without the increase of the widths and horizontal positions of diagram nodes (which should be determined primary by their content, not annotations), thereby leaving the width of the whole diagram unchanged, yet minimizing its height. In some cases, that may be critical to make particularly large diagrams still managable for a human reader.
When this parameter is unselected (false), the wrapping of annotations will be determined only by the widths of their respective component nodes as well as the setting of the parameter: "Annotations | Wrapping | Minimal Width"