Four different ways a SID Altitude is cancelled (there are others) but [1] In the USA “Climb and maintain” [2] in the Canaries you must hear “climb unrestricted” [3] some UK controllers adhere to “climb now” to cancel. [4] others just use climb FL / ALT XYZ and get irritated if you request confirmation. In other words UK controllers are using two different standards for a critical clearance.