TANDBERG 8000 MXP User Manual page 218

Network clocking
The network clock setting specifies the number of physical external clock signals.
RS449/V35 Use RS449/V35 Compatible when the external equipment provides two
Compatible clock signals, one for transmit and one for receive. The difference
between RS449 and V35 is only the cable.
X21 Use X21 Compatible when the external equipment provides a common
Compatible clock signal for both transmits and receive.
General Use
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