SCSI-2
A notched (also called partitioned or zoned) drive has areas of the
medium in which the drive geometry changes. In the simplest case, the
entire medium consists of a single notch. Multiple notches are often
used to increase capacity of the drive. The notch page is used to
indicate the notch for assignment of values to the parameters in the
format device page. By sequencing the notch page through each notch,
the format device parameters of each notch are set. This is usually
done prior to initialization by the FORMAT UNIT command.