Exactly, this is the piece, on which the chant by Fr. Panteleimon is based. Singing in a low position does not mean a different thoretical basis tone.
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Άρα ανήκει σε κάποιον συγκεκριμένο δρόμο;It is based on the famous Axion esti by Karamanis in second plagal mode. The lowest note (and also basis tone) is Pa, sung in a low position in order to avoid high notes.