Activation lock
Activation lock means a control mechanism (either by a physical device directly on the water heater or a control system integrated into the water heater) that is locked by default and contains a physical, software, or digital communication that must be activated with an activation key to enable to the product to operate at its designed specifications and capabilities and without which the activation of the product will provide not greater than 50 percent of the rated first hour delivery of hot water certified by the manufacturer.
Source
10 CFR § 430.2
Scoping language
For purposes of this part, words shall be defined as provided for in section 321 of the Act and as follows -