Adobe Audition dBu values in .sesx file

Dear Adobe-Community,

I would like to work directly with the .sesx projectfile in a texteditor but can not figure out how the dB values are converted to values from 0-1. 

1 = +15 dB

0.65 = 0 dB

0.4 = -9.4

0.2 = -22.9
0.1 = -36.9

....

Does anybody know the exact formula AU is using for the conversion?

Thanks for your help!