The first mode of the 7 is called the Ionian mode or the major mode. It is the first major mode of all of them. The Ionian mode is often used in Rock, Pop, Country, Jazz, and Fusion. Some of the chords that can be used over a Ionian scale are Major, Major Sevenths, Major Ninths, and Elevenths. The intervallic structure is W W H W W W H, Root 2 3 4 5 6 7 Octave.