press fit
I used to have a Mag 21 that had a press fit steerer tube. Slight interference fit is what held it in place. RS had no problem in the early 90s talking about pressing them in and out. Layers have stopped that discussion. Maybe the addition of a locking agent on the subsequent versions. A little quick heat on the crown and pressure to he steerer would remove them easily. Installed with a cooling of the steerer (shrinking of the OD) and heating of the crown (increasing of the ID).