theo bưu chính Nhật thì nó giải thích thế này
SAL stands for Surface Air Lifted and is a service where international mail is handled as surface mail in Japan and the destination country and as airmail between the two countries. The service is faster than surface mail while the cost is lower than airmail.
ttps://www.post.japanpost.jp/int/question/9_en.html
V Wikipedia thì định nghịa như sau:
http://en.wikipedia.org/wiki/Surface_Air_Lifted
SAL, or Surface Air Lifted, is a postal service used to send international mail items. Thirty-nine postal authorities provide this service.[1] It is a cost effective international mail. At first SAL mail is processed and transported by surface in the origin country. Then it is transported by air to the destination country and finally processed and delivered as standard-type mail by the destination postal administration.[2][3] The service is faster than surface mail while the cost is lower than air mail.[2] SAL is more economical for sending heavy items; with light items, it sometimes costs more than air mail.
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