The term 'emblem on a Greek flag' can be summarized as the national symbol of Greece, which is the Greek CROSS. The Greek CROSS is a white CROSS on a blue background, and it has been used as a symbol of Greece since 1822. It is also known as the Greek Orthodox CROSS, and it is a symbol of the Greek Orthodox Church. The Greek CROSS is a symbol of faith, hope, and love, and it is a reminder of the country's Christian heritage.