ID1 is the second of three unique codes provided for each RC4Magic owner, operator, or project.  System IDs consist of four characters that can each be a letter or number, i.e 2876, 2F7D or DFAF.  Although every system has it’s own three unique IDs, they are referred to generically as ID0, ID1, and ID2 on device labels and in documentation.  Each ID supports a separate wireless DMX universe.  Many IDs can be used simultaneously in the same space and cannot functionally interfere with each other.