What dose the 'fixed BN' mean specifically in your paper?

[KoapT]

Thanks for your excellent work but there's something in your 4.2 experiment that confused me.
Does the 'fixed BN' mean just keep the backbone's BN weights(beta&gamma) fixed or freeze all the backbone's weights?

[Howal]

'fixed BN' means that only BN is frozen (use the params from imagenet-pretrained model).