Western Digital Ultrastar DC HC310 Specifications page 312

Cylinder Low (HOB=1)
Cylinder High (HOB=0)
Cylinder High (HOB=1)
LBA (39:32) of the address of the first unrecoverable error.
LBA (23:16) of the address of the first unrecoverable error.
LBA (47:40) of the address of the first unrecoverable error.
Western Digital Hard Disk Drive OEM Specification
298