A Socket is an XML document that contains the semantic model of a specific Target, and may be defined by the manufacturer of the very Target or by any 3rd party entity (as for instance the person who is integrating a new target in the UCH). The document contains and combines variables, constants, commands and notifications, and allows specifying constraints between them. This document has to be conformant with the specification as defined by the ISO 24752 URC standard.

To expose the functionalities of a target it may be used one or multiple Sockets, with each Socket being described by a single SD. E.g. a TV device may have two Sockets and SDs, one for the TV tuner and one for EPG (Electronic Program Guide).