Which of the following reasons may cause BUS_ERR to be reported? (Multiple choice)
A . LOS (The channel of the service board or cross-board is not open; the pin is inverted, and the board is not inserted tightly)
B . OOF (clock loss: clock, frame jitter; no clock board inserted)
C . Receive FIFO overflow (clock, frame header jitter; no clock board inserted)
D . LOF (same as LOS; clock is lost; physical slot and logical slot of service slot are inconsistent)
Answer: ABCD