Materials science knowledge graph and the difference between schema, knowledge graph and ontology is discussed, with the latter involving stronger commitments. The documentation of the commitments is presented in reference to an ISO standard for Top Level Ontologies. In materials science commitments can be derived parly from the scientific method and fundamental physical science principles and foundations. That is how the EMMO ontology has been constructed from the bottom up. The paper will discuss these foundational requirements in relation to the ISO standard for Top Level Ontologies, and how materials science desiderata are fulfilled by EMMO. Based on these solid foundations, examples of the EMMO discipline and domain ontologies will be showcased. In particular, we highlight the CHAMEO ontology for materials characterisation, which underlies the updated "CHADA" CWA 17815:2025. Finally the application of CHAMEO to industrial applications including battery testing and battery digital twin is shown.