Function is_data_schema 

pub fn is_data_schema(schema: Option<&PropSchema>) -> bool

A DATA schema: a shape-less object (any object) or an array of them — Table rows in the core catalog. A literal value there is the author’s data, copied verbatim: no binding, call or $string.<id> inside it is interpreted. A dynamic value AT the position still resolves (and its result is never descended). src/dynamic.ts isDataSchema.