According to Yefim Karskiy, "Western Russian ustav knows ⟨э⟩, e.g. in Miscellany of the 15th c. from the Public Library (manuscr.

"[4] Although the revision of Meletius Smotrytsky’s grammar published in Moscow in 1648 does not include ⟨э⟩ in its alphabet, it does consistently write Этѷмолѻ́гїа (Etymologia), in contrast to Єтѷмоло́ґїѧ in the first edition of 1619.

It was by no means confined to this function in the period, however, as the prevalent spellings реэстръ, маэоръ (beside маеоръ, маіоръ) for modern Russian реестр, майор demonstrate.

The former was used in some early 18th-century Russian texts, but some authorities of the period considered it superfluous, like Mikhail Lomonosov, on the grounds that "the letter Е, having several different pronunciations, could serve in the pronoun етотъ and the interjection ей"[5] and that it was inappropriate to introduce letters solely for use in loanwords.

Even though Russian contains a significant number of loanwords in which [e] occurs after a hard (unpalatalised) consonant, it is still the practice to use the letter ⟨е⟩ for [e], [ɛ]: теннис, сепсис (tennis, sepsis).

The letter ⟨э⟩ is also used in Russian to render initial œ in foreign words: thus Eure (the river in France) is written Эр.

Moreover, its orthography was standardized later than that of Russian (which reached its present form at the beginning of the 20th century), on the basis of the spoken language rather than historical tradition.

Е, however, is only used in the few Mongolian words containing it, Russian loanwords and Russian-style transcriptions of foreign names.