Create Edge Lines

(This functionality is available with the Modelling module)

Create Edge Lines is available from the Edit menu in the Terrain Modelling Task

Create Edge Lines dialog box

Item	Used to
Select Model	Select the model, or TIN, around which the lines are to be created.
Make Break/Boundary Lines	Select this check box to force the lines created to be break and boundary lines. Otherwise the properties will be taken from the currently selected attributes

This command will create line(s) that surround the selected DTM.