How do I know if my child restraint is securely installed?

The child restraint must not move more than 2.5 cm (1 inch) side to side or front to back at the belt path in use. To test this, hold the seat shell at the belt path and try to move the restraint from side to side and front to back. If the seat moves more than 2.5 cm, you must reinstall it, try a different location, or use an alternative installation method. (Page 10)