RDF/Owl schema: arrays vs singular values

Currently in the Owl spec from what I can tell there's no concept of whether a value is singular or one-to-many. For instance RecipeProcess::processClassifiedAs is labeled as an array in both the JSON/GQL schemas, but I see nothing that differentiates it from other values that show up as singular in those schemas.

One thing I've come across in my research is that owl:FunctionalProperty might be used to signify a singular value, but by default all values can be multiple. I've also read that owl:FunctionalProperty is additive such that it can be specified alongside owl:ObjectProperty.

It might make sense to define which fields in the classes are singular. As a usual caveat, I don't know much about RDF/owl so I might be totally off-base by suggesting owl:FunctionalProperty to accomplish this.