In the Part-Editor, use the commands in the:
|•||Geometry menu and toolbar : to add sketch-elements. The toolbar is to the left of the graphic-area.|
|•||Constraints menu and toolbar : to add Constraints to, or between Geometry. The toolbar is to the right of the graphic-area.|
Note: Geometry includes the sketch-element, and its start-Point, end-Point, and centre-Point.
|1.||SHIFT+CLICK a sketch-element - or - its start-Point, end-Point or centre-Point, if the Constraint is between any of those Points.|
The sketch-element and its Constraints show in the Selection-Window.
|2.||Right-click the Constraint|
In the contextual-menu:
To see ONLY Geometry in the Selection-Window:
|•||Click a sketch-element, or its start-Point, end-Point, or centre-Point|
In the Part-Editor, the Constraints toolbar is to the RIGHT of the graphic-area.
MERGE-POINTS : Deletes a Point. You cannot remove a 'Merged Point'.
COINCIDENT CONSTRAINT : Does not delete a Point. You can delete a Coincident-Constraint later and move the Points apart again.
You cannot over-constrain a sketch-element in the Part-Editor (SolidWorks allows you to over-constrain, but you are given a warning).
A Point has 2 degrees-of-freedom (DOF). It you add a 'coincident constraint' between a Point and a Line, you remove 1 DOF, and 1 DOF remains. The Point can slide along the Line.
You cannot then add a new constraint between the same Point and a Point at one end of the Line. A constraint between a Point and a Point would remove 2 DOF, but only 1 DOF that remains.
The sketch-element and constraints added to it, show in the Selection-Window.