The Generalized Discrete Event System specification (G-DEVS) language was introduced by Norbert Giambiasi in the 1990s. This paper first examines the specification of G-DEVS and gives an historical view of N. Giambiasi's works that contributed to this concept. The paper particularly focuses on the extension of G-DEVS to distributed simulation. An example of a G-DEVS model of a ski chairlift system with chair and skier is proposed to show the accuracy gained by using G-DEVS instead of other classical discrete event modeling formalisms. Then, the paper presents how G-DEVS has been extended for interoperability with other components in the context of supply chain M&S coping, with the possibility to compose different model formats at simulation time. Next, the focus is on a G–DEVS editor tool and its extensions: LSIS_DME. The distributed simulation and the HLA standard were used to support the interoperability of various models and simulators.