i think rechael is correct as documented on page 106 of the 2008 pdf manual

The [Save] button saves your song in Band-in-a-Box format. Band-in-a-Box accompaniments are saved
with the file extension *.sgu. If a melody has been recorded the file extension will be *.mgu. The audio
track, if present, is saved as an associated wave file with the song name and the extension *.wav.

that's the theory now if there preference settings the over ride that................


Lenovo YOGA 900 Window s 10 Home 64bit 16GB RAM\2018 13” MacBook Air casio wk7500 presonus audiobox i2 usb interface
casio wk-7500
biab & realband 2023 everything pk both with Current builds