Dell Inspiron 15 (1564, Early 2010) - Manual (Page 328)

328
Ports
S/PDIF Port (Coaxial RCA)
Sony/Philips Digital Interconnect Format (S/PDIF) is a serial interface for
transferring digital audio from CD and DVD players to amplifiers and TVs.
S/PDIF uses unbalanced 75 ohm coaxial cable up to 10 meters with coaxial
RCA connectors or optical fiber terminated with a Toslink (Toshiba link)
connector.
NOTE: There are no differences in the signals transmitted over optical or
coaxial S/PDIF connectors—both carry exactly the same information .
S/PDIF is typically used to transmit PCM and Dolby Digital 5.1, but is not
tied to any sampling rate or audio standard.
S/PDIF Port (Toslink)
Toslink usually refers to the optical version of S/PDIF.
NOTE:
There are no differences in the signals transmitted over optical or coaxial
S/PDIF connectors—both carry exactly the same information.