This is the Orthodox Byzantine Cross. It is used mostly by the Eastern Catholic and Eastern Orthodox Churches. The second cross-bar at top is for the INRI inscription; the bottom cross-bar is His footrest.
INRI is an acronym of the Latin inscription IESVS·NAZARENVS·REX·IVDÆORVM (Iesus Nazarenus, Rex Iudaeorum), which translates to English as "Jesus the Nazarene (Galilean), King of the Jews (Judeans)". The Greek equivalent of this phrase, Ἰησοῦς ὁ Ναζωραῖος ὁ βασιλεὺς τῶν Ἰουδαίων (Iesous ho Nazoraios ho Basileus ton Ioudaion), appears in the New Testament of the Christian Bible.