This read-write OCTET STRING holds a textual description of the interface, intended to include the manufacturer, product name, and hardware version. An administrator reads it, similar in purpose to swDesc but scoped to the physical port's hardware identity rather than a software file set, to identify an unfamiliar interface module. For example, the admin reads sifDescr on an unfamiliar port to identify the manufacturer and hardware revision of the installed interface module before ordering a compatible replacement.