Metadata is organized in the following way: fully-expanded property names
(with IRI prefixes prepended) point to an array of values. Array contains
at least one element. First element is primary and should be used by
default. Element values are objects have the following keys:
"v" - item value as string,
"s" - scheme,
"o" - index in the order of appearing in the source,
"r" - refinement submetadata (organized just like the top-level
metadata).
Metadata is organized in the following way: fully-expanded property names (with IRI prefixes prepended) point to an array of values. Array contains at least one element. First element is primary and should be used by default. Element values are objects have the following keys: