An architecture for designing complex systems includes combining functional decomposition and object-oriented techniques at each level along with specifying links between the levels as well as links between the objects at a level to promote understanding of the system under development and assist both the system design engineers and the hardware and software engineers to develop the system. The present invention resolves the problem by providing an ion conductor represented by a general formula: Al2O4 and having a spinel structure. The first sub-link indicates a relationship between the application requirement and the code module. Said filter module further comprises a spacer element rotatably supported on and releasably attached to said cleaning head, said spacer element defining the minimum spacing between the cleaning head and the internal surface of said filter element.