Methods in accordance with the present invention can include determining a
position of a head along a stroke by locating one or more marker-zones
printed to a reference surface of a disk. The one or more marker-zones
can be printed to a portion of the reference surface as one or more
pulses from a template pattern that can further comprise a plurality of
chevrons. In one embodiment, each pulse can trace the motion of the
stroke along at least a portion of the radius of the reference surface. A
pulse can identify a marker-zone edge when the pulse disappears at some
radius from the center of the disk. By moving the head along the stroke,
the marker-zone edge can be detected and a gross position determined. A
fractional position can be determined by measuring a phase of a chevron
located at substantially the same radial location as the edge.