NAME
	TD_SEEK/ETD_SEEK -- control positioning of the drive heads.

   FUNCTION
	These commands are currently provided for internal diagnostics,
	disk repair, and head cleaning only.

	TD_SEEK and ETD_SEEK move the drive heads to the track specified. The
	io_Offset field should be set to the (byte) offset to which the seek is
	to occur. TD_SEEK and ETD_SEEK do not verify their position until the
	next read. That is, they only move the heads; they do not actually read
	any data.

   IO REQUEST INPUT
	io_Device	preset by the call to OpenDevice()
	io_Unit		preset by the call to OpenDevice()
	io_Command	TD_SEEK or ETD_SEEK
	io_Flags	0 or IOF_QUICK
	io_Offset	byte offset from the start of the disk describing
			where to move the head to.
	iotd_Count	(ETD_SEEK only) maximum allowable change counter
			value.

   IO REQUEST RESULT
	io_Error - 0 for success, or an error code as defined in
	           <devices/trackdisk.h>