Like servers, channels have their own IDs. This value, the cid, is a required parameter for some methods, including set_base_channel and set_child_channels. Also like the sid, the cid can be obtained through the RHN website. Just click on the name of a channel and view the end of the URL. It follows the "=" symbol, as part of a string that resembles the following: "details.pxt?cid=54".