(1) An entire device or feature attached to a processing unit, including required adapters.
(2) A file that is attached to an e-mail message or other electronic document.
(3) A port or a pair of ports, optionally including an associated optical bypass, that are managed as a functional unit. A dual attachment includes two ports: port A and port B. A single attachment consists of one port: port S.
(4) In WebSphere Commerce, a collection of one or more files that are associated to a catalogue or marketing asset. See also attachment asset, attachment target.