(1) (
Common 
Channel 
Signaling)  A communications system in which one channel is used for signaling and different channels are used for voice/data transmission.  Signaling System 7 (SS7) is a CCS system, also known as CCS7.  See 
SS7.
(2) (
Combined 
Charging 
System)  A charging system for EVs in the U.S.  See 
J1772 and 
EV charging.
(3) (
100 Call 
Seconds)  A unit of measurement used in traffic and queuing theory calculations that is equal to 100 seconds of conversation.  One hour of telephone traffic on one line is equal to 36 CCS, which is equal to one erlang (a more common measurement).  CCS can also refer to "cumulative call seconds," which is a measurement of trunk occupancy.  See 
Erlang.
(4) (
Common 
Communications 
Support)  IBM SAA specifications for communications,  CCS includes data streams (DCA, 3270), application services (DIA, DDM), session services (LU 6.2) and data links (X.25, Token Ring).
(5) (
Common 
Command 
Set)  The de facto instruction set between a SCSI-1 adapter and a hard disk.
(6) (
Continuous 
Composite 
Servo)  A technique for aligning the read/write head over a track in an optical disc by sensing special tracking grooves in the disk.