The work of Cross and Freedman on early Hebrew orthography analyzed Northwest Semitic inscriptions in an attempt to describe the introduction and use of matres lectionis in Hebrew spelling. Using this basic typology, Anderson and Forbes have attempted to statistically analyze spelling in the Hebrew Bible in order to draw historical conclusions on the transmission of the Hebrew text. They conclude that the text in general reflects the spelling practice of the Exilic and Persian periods (600-300 BCE). The Pentateuch stands out from the rest as being uniform and conservative in orthography. The basic assumption is that the more archaic the spelling of a book, the earlier it was “canonized”. The Primary History seems to have been canonized in the 6th century BCE, whereas the other books were written or edited after the Exile.