Shape.LengthIU Property (Visio)
Returns the length (perimeter) of the shape in internal units. Read-only.
Data graphic callout shapes (and their sub-shapes) that are applied to the parent shape are excluded from length calculations. If the parent shape is itself a data graphic callout shape, its geometry (and that of its sub-shapes) is not excluded from length calculations.
In versions before Microsoft Office Visio 2003, this property took no arguments.