Edit Bar control: Ok
This tool adds a coincident constraint between two points or a point and an entity (either a line or an arc).
To use the tool, identify two points or a point and an entity.
After creating the coincident constraint you can hover your cursor over the constraint and all the related entities and points will be highlighted.
Shift Modifier
You can also hold the Shift key down whilst identifying them to include more points or entities. When you have finished identifying them, all points will be constrained to coincide. If the constraint also includes a line or arc then the points are constrained to lie somewhere along their path.
After identifying two unconnected points whilst using the Shift modifier the Ok button becomes active on the edit bar: 
You can now click this button to finish the tool and apply the constraint.
Pre-selected Entities
Alternatively, you can select two or more entities and then start the tool. The coincident constraint will then be added to any coincident points.
NOTE: Whilst this tool can be used to move points and entities so as to satisfy the constraint, it is recommended that entities are created in the desired position.