Your computer must request resend from the server before proceeding. This will cause a complete halt of the game or small stuttering, depending on your ping. It can be compensated. A non-action sequence is received. While the game is under pause, you will keep receiveing a steady stream of those.
White lines are completely normal and does never indicate any problem.
A replicated action is received. It can be compensated. An action was skipped. This means that server action buffered overfilled and server had to drop one of the actions you did. This is similar to BLUE and they usually come in pairs.