Assimilation and dissimilation of vowels as an important factor of formation of the Christian personal name’s forms in the language of pre-national period

The article shows the role of the assimilative and dissimilative changes in vowel sounds in the process of development of the foreign-language Christian personal names of the Russian language and the reflection of this process in the Tver official words of XVI - XVII centuries. - period of the formation of antroponymic standards.