Saved file has 31 data columns but I'd expect 1 per channel

in OpenBCI_GUI
I'm trying to import the saved data from the OpenBCI GUI to EEgLab in Matlab.
But I don't understand this data.
There are 31 columns of data. But I'm using the 8-channel Cyton, so I'd expect 8 columns of data, 1 per channel.
What are all these columns?
Comments
https://docs.openbci.com/Software/OpenBCISoftware/GUIDocs/#cyton
TY!! @wjcroft