Soft/Rigid Bodies > Create Constraint >
Sets the options when creating a constraint. Here are the options:
If you want to specify the constraint’s initial position, turn on Set Initial Position and enter X, Y, and Z values for the position.
If you don’t turn on Set Initial Position, a constraint is created either at the midpoint between the two rigid bodies (extending from one rigid body’s center of mass to the other’s center of mass), or at the center of mass of the rigid body, depending on the type of constraint.