squawk 7x00 is reported and shown


I realize this is meant to convey an emergency but is often an error. But my question is about “is reported as shwon”. How is it shown?


The aircraft get a different color.


I have seen it about once a day on my receivers. They show up in the list with a yellow background.
I check other receivers and they always show them with a valid code so I assume that they are just decoding anomalies.