unity rigidbody constraints

C#
m_Rigidbody = GetComponent<Rigidbody>();
        //This locks the RigidBody so that it does not move or rotate in the Z axis.
        m_Rigidbody.constraints = RigidbodyConstraints.FreezePositionZ | RigidbodyConstraints.FreezeRotationZ;
Source

Also in C#: