On a special rig, I'm pretty sure. I don't know how the RK06 alignment pack works, but I am familiar with the RK05 (our machine had them, and we had to realign one after a head crash), and I assume it's probably similar; it had to have been created on a special rig (the exact nature of which I don't know, but I know a normal drive couldn't write it). For the RK05, the alignment pack has alignment tracks with alternating sectors written a couple of thousandths of an inch offset from the track's nominal center line; when one watches the head's output on a 'scope (at a timebase sufficient to show pairs of sectors), if the output for both sectors in a pair is at the same amplitude, the head is correctly aligned. If not, it's easy to see on the 'scope - one has higher output than the other. Noel