Where is an affine transformaiton matrix of EPI to T1w in fmriprep output folder

Hi stars (and superstar @ChrisGorgolewski),

I was looking for the EPI->T1 transform and came across this post. I am a little confused and was hoping someone could clarify.

Perhaps this was different at the time of the original post, but I see several transforms in …/bold_reg_wf/bbreg_wf/:

bbregister/
fsl2itk_fwd/
lta2fsl_fwd/

Are these different formats of the same transform, or altogether different transforms? I see the folder “compare_transforms” so I am guessing the latter - i.e. the above are compared and then the “best” one is selected?

Is the “chosen transform” stored in /mri_coreg/ ?

Cheers!