I apologize if this has been asked before. I have searched and searched to no avail, it seems questions about getting rid of over/underfull boxes drown out any questions about how to produce the marks.
I have a custom command, and I should like to mark each line that contains this custom command with a marker similar to the over/underfull marker. Ideally it would
- mark the lines in the output when in draft mode
- either not produce warnings on the command line, or produce a custom message detailing the count
pointers, big or small, in the right direction are much appreciated :)