An SMB returns error information to the client in the Status field. Protocol dialects prior to NT LM 0.12 return status to the client using the combination of Status.DosError.ErrorClass and Status.DosError.Error. Beginning with NT LM 0.12 CIFS servers can return 32 bit error information to clients using Status.Status if the incoming client SMB has bit 14 set in the Flags2 field of the SMB header. The contents of response parameters is not guaranteed in the case of an error return, and must be ignored. For write behind activity, a subsequent write or close of the file may return the fact that a previous write failed. Normally write behind failures are limited to hard disk errors and device out of space.