It's B11. The top 4 notes of B11 chord are the same as A6 or F#m7. Stacking 3 of those notes on top of B and D# makes a very useful and fat B9th chord. adding the E on top gets us into familiar A6th territory for melodies.
B11 seems exotic at first, but it's very pretty once you get used to it.
- keyless Sonny Jenkins laps stay in tune forever!; Carter PSG
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