Open Hardware and the IoTaWatt trademark
IoTaWatt is a trademark of the creator of the IoTaWatt software, Bob Lemaire of Wolfeboro, NH, USA. It is used by IoTaWatt, Inc. by permission and use to identify any other commercial product, without express written consent, is prohibited. The intent is not to restrict the technology, but to insure that hardware branded as IoTaWatt conforms to the open specification, has regulatory and safety approvals, and will reliably perform with the open and free IoTaWatt software.
In other words, you can build and sell an open hardware IoTaWatt device, but you can't call it an IoTaWatt without the permission of the trademark owner.