Edit > Select > Boundaries selects one or more natural boundaries on a point or polygon object.
The parameters are:
Compute All button - To select all natural boundaries of the object, click this button. To select one natural boundary, point to it in the Viewing Area and left-click it.
Expand button - increases the thickness of the selection near the natural boundary. Press this button any number of times to continue increasing the width of the selection.
OK button - closes the dialog and retains the selection for action by another function.
Cancel button - clears the selection and closes the dialog.
To select one or more boundaries:
Activate a point or polygon object that is not completely closed.
Select Edit > Select > Boundaries.
Click Compute All or select one or more boundaries in the Viewing Area.
Optionally, press the expand button until the width of the selection about the boundary (or boundaries) is sufficient.
Click OK.