QSOs can be color-coded in the log tables for your convenience. RUMlog uses magenta text color to indicate invalid DXCC QSOs. The user can select the background color. You can choose the color while logging from the provided popup in the logging area, or you can change it later. Select one or more QSOs in the table and go to: Menu–>QSO–>Color code.
This also works in the Search windows, allowing you to mark found QSOs on the fly.
You will find the Color code popup on the right hand side of the quick search section. It may be necessary to widen your window.
You can also chose a color for the QSOs during a contest log or ADIF import.
The color code will be exported in an ADIF file, and it can be reimported. However, this is not an ADIF conform function, and so it only works in RUMlog.