Official seals for Chinese emperors were square and large. High government official’s seals might also be square but smaller; usually about one inch across during the Han dynasty (206 BC–220 AD). Lesser officials sometimes used half-square seals rectangular in shape. Any other shape than square or rectangular is considered informal. Seals with either the last name only or with the full name are often square and used near the artist’s signature while informal seals may be used anywhere on an artwork.