A very important source for injury surveillance is the E-codes in hospital discharge data. E-code is a secondary diagnosis code for the external cause of an injury. If a discharge record has an injury principal diagnosis in a range of ICD-9 800-999, and E-code (E800-E999) as a secondary diagnosis is desired. A designated E-code field (Box 77) is allocated in the Uniform Billing 1992 (UB92). The quality of E-code data has been improved since 1992.