Schoolgirls in tradi...: Schoolgirls in traditional `Ao Dai` dresses and conical hats pass by Hanoi's Opera House. The traditional long white dresses are the formal uniform of many high school girls in Vietnam. But they are not just popular with young girls. The Ao Dai's different colours and materials indicate the wearer's age and status, eg white for young girls, pastel shades for slightly older women, rich colours for married women and satin materials for the elderly. /KTS