Esperanto letter R

The Esperanto letter R (called ro in Esperanto) represents IPA phoneme /r/, like "r" in Spanish or Italian "Roma". However in the different editions of the Fundamento de Esperanto, Zamenhoff defined "r" as the "r" in the Fundamento ' s language. This means that /r/ can be realized as [r]  (alveolar trill),  [ɾ]  (alveolar tap), [ʁ] (uvular fricative), or  [ɹ]  (alveolar approximant, like English "r").