Answer
Here?s how the firmware is decided for the 40NBT (the 40L only has one flavor of firmware) 40NBT has three different firmware and each one utilizes only two factors out of three. (among A rate, N rate, CCX) It checked the 5GhzChanMask key first and check CCX setting to determine which firmware to load. (the table below looks broken in plain text. Please refer to the attached) 5GHzChanMask CCXfeatures Bin File A N CCX 0 Don?t Care SDC40NBT_GN.bin Y Y Not 0 Off SDC40NBT_AGN_NOCCX.bin Y Y Not 0 On SDC40NBT_AG.bin Y Y