A pharmaceutical composition is provided which comprises an isotonic solution of an 0. The communicative coupling supports a variety of functions such as, for example, device discovery, content discovery, and seamless transfer of media between the two or more devices. With knowledge of the speaker characteristics, audio output can be equalized appropriately, and an amplifier of the media device, for example, can prevent exceeding the maximum power handling capability of the speaker. The resident external controlling interface sends third and fourth commands representative of the first and second commands, respectively, to a digital command station for execution on the digitally controlled model railroad.