They are intended to give local residents and communities the confidence to say "no" to uninvited salespeople or to warn rogue traders and cold-callers they are being watched.
Eu bwriad yw rhoi’r hyder i drigolion a chymunedau lleol ddweud “na” i werthwyr diwahoddiad neu rybuddio masnachwyr twyllodrus a galwyr diwahoddiad bod rhywun yn eu gwylio.