The IPA letter was adopted in 1921 as ⟨ʚ⟩, alongside unrounded ⟨ᴈ⟩, then abandoned. It was brought back in 1993. However, due to a confusion of sources, this form was thought to be an error, and it was replaced with the current form ⟨ɞ⟩ (closed ⟨ɜ⟩ rather than the intended closed ⟨ɛ⟩) in 1996. The original turned epsilon ⟨ᴈ⟩ had been replaced with a reversed epsilon ⟨ɜ⟩ sometime between 1957 and 1989.
In some sources, such as LAMSAS, ⟨ɞ⟩ and ⟨ʚ⟩ have different values.