You can follow these steps to use all different option of the head lock to:

1. Create a new task.
2. Add Move Head node.
3. Add to this node head pose by clicking “+HEAD POSE”
4. Add Move To node
5. Add to this node arm pose by clicking “+ARM POSE”
6. Add another Move To node.
7. Move joint 0 to a different position using JOINTS panel.
8. Move joint 3 to a different position using JOINTS panel.
9. Add to the second Move To node arm pose by clicking “+ARM POSE”
10. Select all nodes in the task by holding CTRL.
11. Copy the nodes (CTRL+C)
12. Paste them twice (CTRL+V, CTRL+V)
13. Change the second Move Head node “lock to” to “Arm - J0”
14. Change the third Move Head node “lock to” to “Active Endpoint”
15. Before running the task you may want to slow down the task by changing “task playback rate” in the start node to 0.5.
16. Run the task. Watch the different behavior of the head during the task.