A method for controlling detached lighting units uses source light of a capable flashlight to communicate information. The capable flashlight encodes an ID Tag in modulated light, and the detached lighting units recognize the specific ID Tag and responds, for example by activating and creating illumination. A user can illuminate selected areas by shining the beam of the flashlight on detached lighting units to selectively activate them, and since the detached lighting units only respond to the encoded light, unintended activation is avoided. In addition to the encoded ID Tag, mode information can be included such that the detached lighting units can respond in a number of ways, such as selected periods of activation. Stored ID Tags can be transferred and thus shared using the same modulated light. ID Tags can be randomly re-assigned, and the new value shared among other flashlights and detached lighting units, creating a coordinated set.