Hitachi HDS723020BLA642 Specifications page 176

Cylinder High (HOB=1)
CCTO (Error, bit 0)
SE (Status, bit 5)
LBA (47:40) of the address of the first unrecoverable error.
CCTO bit shall be set to one if a Command Completion Time Limit Out error has
occurred.
SE (Stream Error) shall be set to one if an error has occurred during the execution
of the command and the RC bit is set to one. In this case the LBA returned in the
Sector Number registers shall be the address of the first sector in error, and the
Sector Count registers shall contain the number of consecutive sectors that may
contain errors. If the RC bit is set to one when the command is issued and a
UNC, IDNF, ABRT, or CCTO error occurs, the SE bit shall be set to one, the ERR
bit shall be cleared to zero, and the bits that would normally be set in the Error
register shall be set in the error log.
Hitachi hard disk drive specifications
176