Shipments by carrier type

Airmail – Transportation is made via air between the outbound and inbound country.

SAL (JP)

SAL (aka Surface Air Lift) – Transportation is made via air between the outbound and inbound country, as well as between the other countries, if a Direct Operation is not possible.  The rest of transportation is made by other means of transportation than air, when the mail is arrived in the destination country and it’s required.

Surface Mail – Transportation is made via sea, railroad or highway between the outbound and inbound country.

Note: Those may be not valid for the designations private courier services use.