Paul Erlich tetrad (pitch values in cents). This, in jazz terminology is an add6, add9 (6/9) chord with no 5th, in typical jazz fashion.
alternate tuning
Relative to what would seem ideal just tuning of 36:45:60:80 (1/1:5/4:5/3:20/9), the intervals are expanded a bit, probably to bring the outer 9:20 cloaser to the much more concordant 4:9.
