*Unique B/L Identifier: U.S. Customs' standardization: four-alpha code unique to each carrier placed in front of nine digit B/L number; APL's unique B/L Identifier is "APLU". Sea-land uses "SEAU". These prefixes are also used as the container identification. | *Unique B/L Identifier: U.S. Customs' standardization: four-alpha code unique to each carrier placed in front of nine digit B/L number; APL's unique B/L Identifier is "APLU". Sea-land uses "SEAU". These prefixes are also used as the container identification. |