In the illustration above, the additional directory is named c0t6. That simply reflects a particular system's device naming conventions. The directory name on your system could be different, though it would have the same format.
The CDs themselves, however, follow a convention similar to diskettes, in that they are mounted beneath the directory belonging to their device:
As a result of this arrangement, a system with one diskette drive and one CD-ROM drive would have the following /vol/dev file system: