There have been some problems with the Nowell transcription. However modern scholars have compared Nowell's transcription of other manuscripts, where the originals are still available, enabling a picture of the conventions Nowell used to be built. This model was then applied in the correction of his transcription of the Burghal Hidage Ortho manuscript. It seems that Nowell did not understand the subtlety of the phonetics of the Anglo-Saxon written language and would therefore substitute, using his knowledge of Elizabethan grammar, what he saw as an equivalent letter, thus giving the Anglo-Saxon word a completely different sound and meaning. Other issues included for example, the original scribes' use of an open Old English ""a"" which Nowell incorrectly copied as a ""u"".