Andy:
Daniel is correct about X-10. It is a power line carrier protocol for home automation. There are transmiters, and receivers in this type of system. Your Pronto is an X-10 transmitter since it is capable of transmitting an X-10 IR signal with the proper CCF file that you can find on this web site. Other transmitters are RF hand held remotes, and home automation controllers that also transmit X-10 signals based on time, occurence of an event, or on user demand. Receivers are things like wall switches, lamp modules, and appliance modules.
To get started using your Pronto with X-10 you need and IR transceiver, followed by X-10 controllable wall swtiches or lamp modules to control lighting. We have helped many people on this forum with getting started with X-10 and would be happy to explain to you in more detail how it all fits together. We also carry a complete line of home automation gear and are willing to take the time to explain how it works and answer your questions. Everything that Smarthome has in their catalog, we also sell.
Please send me an e-mail or visit our web site for more contact information if you have any questions or would like to order the equipment you need to get started.
Robert
RCI Automation
rciautomation@csi.com[Link: ourworld.compuserve.com]