Above Theodora's face is the title 'Episcopa,' with the feminine ending, signifying a Bishop who is a woman

Catholic New Times, May 4, 2003

Above Theodora's face is the title 'Episcopa,' with the feminine ending, signifying a Bishop who is a woman. That's (if you're counting) two proofs of female ordination. One; the female image. Two; the female word for 'Bishop.' Around her head is a square frame, signifying that she was living during the time of the portrait.

This mosaic is taken from a Church of St. Praxedis in Rome. Circa 900ad.