new seal employing the same symbols and design-elements as those used by his father. It is likely that this practice was a factor in the emergence of hereditary heraldry in western Europe in the 12th century. Ecclesiasticism Ecclesiastical seals are frequently mandorla-shaped, as in the shape of an almond, also known as vesica-shaped. The use of a seal by men of wealth and position was common before the Christian era, but high functionaries of the Church adopted the habit. An incidental allusion in one of St. Augustine's letters (217 to Victorinus) indicates that he used a seal. The practice spread, and it seems to be taken for granted by King Clovis I at the very beginning of the Merovingian dynasty. Later ecclesiastical synods require that letters under the bishop's seal should be given to priests when for some reason they lawfully quit their own proper diocese. Such a ruling was enacted at Chalon-sur-Saône in 813. Pope Nicholas I in the same century complained that the bishops of Dôle and Reims had, "contra morem" (contrary to custom), sent their letters to him unsealed. The custom of bishops possessing seals may from this date be assumed to have been pretty general. In the British Museum collection the earliest bishop's seals preserved are those of William de St-Calais, Bishop of Durham (1081–96) and of St. Anselm, Archbishop of Canterbury (1093–1109). Architects, surveyors and professional engineers Seals are also affixed on architectural or engineering construction documents, or land survey drawings, to certify the identity of the licensed professional who supervised the development. Depending on the authority having jurisdiction for the project, these seals may be embossed and signed, stamped and signed, or in certain situations a computer generated facsimile of the original seal validated by a digital certificate owned by the professional may be attached to a security protected computer file. The identities on the professional seals determine legal responsibility for any errors or omissions, and in some cases financial responsibility for their correction as well as the territory of their responsibility, e.g.: "State of Minnesota". In some jurisdictions, especially in Canada, it is a legal requirement for a professional engineer to seal documents in accordance with the Engineering Profession Act and Regulations. Professional engineers may also be legally entitled to seal any document they prepare. The seal identifies work performed by, or under the direct supervision of, a licensed professional engineer, and assures