R. hub, Shimano "XT Deore". It has a spline at the non-drive end for disc
rotor attachment. This is not the 24-spline type but the many-more file-pitch
spline.

This rotor attachment isn't "center lock", what is it called? Just "Shimano
type"?

I'm looking for an adapter to ISO 6-bolt rotors. Any suggestions?

Thanks.