In most European member states, employees stay with a company for over ten years. During this time, people gain valuable experience and build up expertise that is lost to production companies when employees leave. Despite increasing digitalisation, there will still be processes, especially in individual production, that require experts. Ontologies are an established method for formalising knowledge. Standards are needed to ensure interoperability. However, not all reference models are based on the standardised basic formal ontology. To the best of our knowledge, there are also no references for modelling human-bound production steps. We have developed the freely accessible ROXANA ontology based on actual use cases from special-purpose machines. This ontology is based on the basic formal ontology and uses references from the common core ontologies and the industrial ontology foundry. The difficulty with expert-bound process steps in production is individuality and complexity. The design of special-purpose machines is individual, as are the machine-specific documents and the associated workflows. This paper presents the ontology, explains it using practical examples, and shows its implementation in a real software-based expert system.