This structure is used in the following IOCTL fns:
    440dH 42H (format track on logical drive)
    440dH 62H (verify track on logical drive)

    DvRq 13H  (generic IOCTL for block devices)

  Offset Size Contents
  ▀▀▀▀▀▀ ▀▀▀▀ ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
    +0     1  rSpclFns     must be 0
    +1     2  wHead        head to read/write
    +3     2  wTrack       track (cylinder) to read/write
           5               size of an IoctlFmtVrfyTrackRec

   Notes: DOS device drivers do not keep a track layout table for each
          logical device.  Before formatting a track, use a generic IOCTL
          Set Parameters (440dH 40H) call to set the interleave etc. for
          the media in the drive.

See Also: fn 440dH (Generic IOCTL for block devices)
          Device Drivers
          DOS Functions