Specify the guaranteed minimal width (in pixels) of the rectangle, in which the annotation text is wrapped.
In diagram, annotations are typically displayed under the nodes depicting the respective components. So, the width into which the annotation is wrapped is never smaller than the width of its component node. However, some component nodes may be too small (narrow) to serve as a base for the annotation wrapping.
Note that the value of this parameter will affect the total width of the diagram. If you want the generated diagrams to fit into relatively narrow frame (for instance, to print them on sheets of paper), you may need to reduce the value of this parameter.