What is the data structure of the keyfobs and handhelds?

The data structure for the Holtek encoder and decoder is shown in the Application Notes. The Holtek-based Keyfob and Handheld transmitters incorporate an LR Series transmitter combined with a Holtek HT640 encoder, so it is possible to use an LR Series receiver and a microcontroller to decode the transmission. This can provide more functionality to a system by allowing the address bits to identify an individual transmitter.