A processor-readable medium comprises processor-executable instructions.
The instructions are configured for scanning a reference pattern on a
disc to determine a first radial position of the laser, wherein the
reference pattern is located at a first nominal distance from a center of
the disc and extends to a second nominal distance from the center of the
disc, wherein the first and second nominal distances are accurate to
within a nominal runout tolerance. The instructions are also configured
for reading media ID data on the disc only when the radial position is
greater than or equal to the first nominal distance plus the nominal
runout tolerance and is less than or equal to the second nominal distance
minus the nominal runout tolerance.