The sender is requesting to be identified to the system at address <device>, where <device> is a one-word mnemonic describing the class of peripheral or machine, e.g. icon or battery. No two connected devices may have the same address at the same time. For peripherals, the add message should be sent in response to an on_rez() or attach() event, or in response to the probe message. The controller will respond with either add-confirm or add-fail.