Here are some common abbreviations that you will will come across when using digital modes in ham radio. These abbreviations have been long time used for CW and now have been carried over to other digital modes.
| Voice | Code | Situation |
|---|---|---|
| Go ahead | K | Used after calling CQ, or at the end of a transmission, to indicate any station is invited to transmit. |
| Over | AR | Used after a call to a specific station, before the contact has been established. |
| KN | Used at the end of any transmission when only the specific station contacted is invited to answer. | |
| Stand by or wait | AS | A temporary interruption of the contact. |
| Roger | R | Indicates a transmission has been received correctly and in full. |
| Clear | SK | End of contact. SK is sent before the final identification. |
| Leaving the air or closing the station | CL | Indicates that a station is going off the air, and will not listen or answer any further calls. CL is sent after the final identification. |
Source: arrl.org