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Appendix D. Glossary
61200275L1-1 TSU IQ+ User Manual D-5
CTS
clear to send. A signal on the DTE interface indicating that the DCE is clear to
send data.
CV
code violation. Cyclic redundancy check (CRC) errors and frame bit errors when
in ESF (extended super frame) format, or bipolar violations and frame bit errors
when in SF (super frame) format.
data link
See FDL.
dB
The standard abbreviation for decibel. A decibel is a unit of measure for signal.
A decibel is usually the relation between a transmitted signal and a standard sig-
nal source. Therefore, 6 dB of loss would mean that there is a 6 dB difference
between what arrives down a communications circuit and what was transmitted
by a standard signal generator.
DCE
data communications equipment. A device that provides all the functions
required for connection to telephone company lines and for converting signals
between telephone lines and DTE. Also see DTE.
DDS
digital data service. AT&T private line service for transmitting data over a digi-
tal system. The digital transmission system transmits electrical signals directly,
instead of translating the signals into tones of varied frequencies as with tradi-
tional analog transmission systems. Digital techniques provide more efficient
use of transmission facilities, resulting in lower error rates and costs than analog
systems.
DE
discard eligibility. A user-set bit indicating that a frame may be discarded in
preference to other frames if congestion occurs, to maintain the committed qual-
ity of service within the network. Frames with the DE bit set are considered
excess data.