From Connolly and Dodge, The Ancient City
Metics or resident aliens with their involvement in various businesses were very important to the Athenian economy. They were not and could not become citizens, but nevertheless had to serve in the military and pay a poll-tax. They, however, could not participate in the political life of Athens. If indeed the three figures above are metics, then Athens at least honored them by allowing them to participate actively in Athens' greatest festival.