Carrier is a mechanism by which information is transported over distance or time.
For manuscripts or printed documents, the carrier consists of a base and the medium, typically paper and ink. For photographs, the carrier includes the base, commonly paper, film, glass, or metal; the substance that forms the image, such as silver or dye; and any binder, such as gelatin or albumen. For digital information the carrier may be physical, such as a disk or a tape with a magnetic or optical layer, or a signal convede by radio frequency or electrical current.
"Carrier" is in the CPC Code "8411"