Sanity documenta are equivalent to classes. A property can refer to another document or create a nested object on the original document. Objects are sadly not directly queryable and can not be referred to by other documents. Muna nest data for quick editorial experience for the end user. Converting Sanity data to JSON-LD could easily convert objects to documents and poplate a rdf triplestore for detailed querying. A conversion of a dataset using Muna to rdf should treat document and object as equals.
Common properties are described in
./src/props/index.js as properties are reused extensivly. The same property name can still be reused in document or object for more spesific ranges.
Getting the balance right between Sanity documents and objects is a bit tricky coming from the world of RDF. As of sept. 2020 creating a document when creating the reference is not user friendly. A CIDOC-CRM class such as Birth is an object in Sanity for a smoother user experience.
Ideally one could query directly for objects with GROQ, but that is not possible. With GROQ you need to find all persons with a birth object and matching date and filter the results.
A SPARQL would query for the class Birth with a relation to a timespan matching the date and return all matching persons.
The reasoning behind having few documents and many objects is user friendliness. Muna tries to strike a balance between expressivness and useability. The query example illustrates