==Digital equivalent SPDIF== 

 "Digital audio signal being sent through wire can use several formats including optical (ADAT, TDIF), coaxial (S/PDIF), XLR (AES/EBU), and ethernet, especially for large digital audio consoles." 

 I'm a bit confused on this issue.  Is the S/PDIF standard applicable to both optical mediums as well as coaxial mediums?