The term "charter" covers a range of written legal documentation including diplomas, writs and wills. A diploma was a royal charter that granted rights over land or other privileges by the king, whereas a writ was an instruction (or prohibition) by the king which may have contained evidence of rights or privileges. Diplomas were usually written on parchment in Latin, but often contained sections in the vernacular, describing the bounds of estates, which often correspond closely to modern parish boundaries. The writ was authenticated by a seal and gradually replaced the diploma as evidence of land tenure during the late Anglo-Saxon and early Norman periods. Land held by virtue of a charter was known as "bookland".