Romanian major scale
The Romanian major scale also known as the Lydian Dominant ♭2 scale is a heptatonic scale subset of the octatonic scale with an omitted 3 degree. It is noted for its flattened 2nd and sharpened fourth degrees, the latter a distinctive feature of Romanian traditional music. It has the following interval structure in semitones: 1, 3, 2, 1, 2, 1, 2, giving it the notes C, D, E, F, G, A, B in the key of C. Though it is called a major scale, it is typically played over a C13 dominant chord. This is an enharmonic mode of B Harmonic Minor, along with D Harmonic Major. The root note of F Harmonic Major is raised a semitone to F, and the root note of D Aeolian Dominant lowered a semitone to D. There is also a ♮6 with the D Super Lydian Augmented scale, lowering the B♮ to B.
As the Romanian major scale is a subset of the octatonic scale with no 3, it should have diminished seventh chords, particularly from its second note. This scale's 4th and 6th notes have minor or major chord, while the root only has a major chord.
The 5th mode, Jazz minor flat 5, also known as Jeth's Mode, is a jazz minor or melodic minor scale with a flattened 5th, and is named after Dutch composer Willem Jeths. It can also be thought of as a whole half diminished scale omitting the augmented fifth. It can be used for soloing instead of regular jazz minor. The Jazz minor flat 5 mode in C contains the notes C, D, E, F, G, A, B, which has the formula 1, 2, 3, 4, 5, 6, 7. This is an enharmonic mode of E Harmonic Minor, along with G Harmonic Major. The root note of Bb Harmonic Major is raised a semitone to B♮, and the root note of G Aeolian Dominant lowered a semitone to G. There is also a ♮6 with the Gb Super Lydian Augmented scale, lowering the E♮ to E.