About Same-Point Constraints
A constraint is a condition defining the geometry of the entity or a relationship among entities. Coincident entities introduce same-point constraints by default. Same-point constraints are created between endpoints in the following scenarios:
• Creating 2D geometry with coincident endpoints
• Dragging an endpoint and snapping it to a stationary endpoint
• Rigidly translating an entire entity and snapping one of its endpoints to a stationary endpoint before selecting a geometry tool or an entity
• Snapping an endpoint to an endpoint belonging to a background entity projected onto the sketch plane
• Snapping to an entity when creating geometry
• Snapping when dragging an entity in the preselection mode
• Projecting coincident endpoints of a background entity onto the sketch plane
Entities with same point constraints remain connected even when you drag them. Since holding down the SHIFT key prevents snapping, endpoints cannot be made coincident. In this case same-point constraints are not created when you bring endpoints near each other. If endpoints already have same-point constraints, hold down the SHIFT key to break the constraints.