Well for the sake of others that might read this I will talk about all 5 holes on the bottom of Coda.
With the flute flipped over on its back and the mouthpiece facing away from you.
The top two square/half moon looking holes is the voicing windows for both upper and lower octaves and where the fipple edge/blade is.
The next two holes down, a large left and a very small right hole are the thumb tone holes.
The very small right thumb hole is only used for C#/Db and the Alternate D#/Eb fingering.
The last and lowest large hole is a tuning hole that needs to be always open and clear.