Deciphering Airbnb bookings sheet?

[James Carlson]

I'm looking at an excel sheet of Airbnb bookings for a client of mine. It looks a little different than others I've seen. Anyone ever seen a printout from Airbnb that includes a column title "m_nights_altered" as seen below?

Is it as simple as the guest or someone has altered the total nights stay? And if so, just that "-4" means they shortened the stay by four nights and "30" means they extended the stay by 30 days?

Finally, would the "nights" column would be the total number of nights stayed before or after the "nights altered"?