It may happen that, at the start of a scheduled CW rag chew, the frequency is in use, but only one side can hear that it is in use.
- A cannot hear the existing QSO.
- B can hear the existing QSO.
- A begins by sending "QRL?" ("is this frequency in use?")
What should B do now? If B responds to A's query with "QRL" ("this frequency is in use"), there is a danger of the stations in the existing QSO thinking that this is directed to them, and having them cease or change frequencies as a result. That doesn't seem right; they were there first.
How can B let A know that the frequency is in use while causing the least disruption to the existing QSO?