is carrier of at all times has role represented by indicator value la valeur de l’indicateur il valore dell'indicatore indicator-role indicateur (rôle) ruolo di indicatore complex system component composante de système complexe componente del sistema complesso indicator indicateur indicatore http://purl.unep.org/sdg/SDGIO_00000002 A complex system component with an indicator role. Due to the SCO focus on complex systems, indicator classes have been designed referring specifically to complex systems. Nevertheless, future implementations may broaden the space of application to also systems. SCO indicator classes have been designed referring to the characterization of sustainable development indicators (SDGs indicators) proposed by SDGIO. we aimed to deepen this characterization and establish upper-level classes for SDGIO ones. complex system indicator system indicator Une composante de système complexe ayant un rôle d’indicateur. Una componente del sistema complesso con un ruolo d’indicatore. provisional