If you are talking about non EFIS (analogue), then you may be referring to the red warning lights which are situated inside the indicators on the N1, N2 and EGT indicators. These lights illuminate when an engine paramater has been exceeded and remaim on until the parameter is reduced below the limit.
On the EFIS displays the ‘dots’ are situated above the indicator and do the same job.
If you are talking about something else, then I am stumped.