Linux has a single file system starting at the root "/". Everything has to be "mounted" to it. So you create a directory, e.g. "/mnt/cdrom" and the CDROM is then attached to that directory. If you think about it, it makes more sense than having a logical limit of 26 different drives. In a networked environment, it's easy to exceed 26.
Look up the HowTo on mounting devices for more info.