Phonology
The charts show the vowel and consonant systems of the East Franconian dialect in the 9th century. This is the dialect of the monastery of Fulda, and specifically of the Old High German Tatian. Dictionaries and grammars of OHG often use the spellings of the Tatian as a substitute for genuine standardised spellings, and these have the advantage of being recognizably close to the Middle High German forms of words, particularly with respect to the consonants.
Read more about this topic: Old High German