This document amends the Customs Regulations pertaining to air commerce to provide that once an air waybill number is used on an air cargo manifest, one year must elapse before the same air waybill number may be used on another air cargo manifest. Current regulations prohibit the re-use of an air waybill number for three years after it is used on an air cargo manifest. This document also specifies that air cargo manifests must reference an 11- digit air waybill number for each air waybill it covers.