It would be useful but strictly only needs a Local Rule. A common convention is green tops.Slight drift but..
I am interested in the OP information that the red stakes indicated a PA but did not define it. We have similar markers for two areas of OOB where white stakes with black tops indicate a nearby OOB but do not define the OOB. Do the red stakes in OP‘s query need to have a means of indicating that there are not defining the PA?