Watch the 1 5 1 9 Structures online guitar lesson by Brad Carlton from Guitar Lab: Open String Universe

This lesson uses a root fifth root ninth structure on the 6th through 3rd strings combined with the 2nd and 1st strings open.

Voicing 1 is a CMaj9 voiced 1 5 1 9 7 3. Ionian and lydian apply. Voicing 2 is a C#m9 voiced 1 5 1 9 b7 b3. This chord is a subbset of dorian and aeolian.