- Location is a fixed place.
- Position is a variable place.
use path data with Geometry
go.Shape.defineArrowheadGeometry('Standard', 'F1 m 0,0 l 8,4 -8,4 2,-4 z');
go.Shape.defineArrowheadGeometry('Backward', 'F1 m 8,0 l -2,4 2,4 -8,-4 z');
go.Shape.defineArrowheadGeometry('Triangle', 'F1 m 0,0 l 8,4.62 -8,4.62 z');