When edges of the part are locatable, you can select them to complete other operations. For example, you can use part edges to place a dimension between the current profile elements and an existing edge.

It can be useful to make the edges of the part non-locatable. For example, when drawing a simple profile on a complex part, you may want to make the existing edges non-locatable until you draw the profile elements. You can then make the edges locatable again to add positioning dimensions or relationships between the profile and the parts edges.