For diamond-level services, the conditions that trigger SNCP protection switching include SF and SD. Which of the following alarms are triggered by SF? (Multiple choice)

When R_LOS, RLOF, R_OOF, MUT_LOS and other alarms appear on the device, it means that the service has been interrupted.

The fully standardized optical transport unit OTUK is an OTUk frame that fully complies with ITU-T G.709 recommendations, and it has the precise field format, field size and type specified in ITU-T G.709.

The decrease of signal-to-noise ratio at the receiving end will not cause bit errors.

Which of the following descriptions about OSC and ESC technology is correct? (Multiple choice)