For all types of objects, additional data can be stored in a "details" field using the JSON format. RFC4627 describes what constitutes valid JSON -- for example, the top level element needs to be an object (hash) or an array. Unlike properties, the values stored in the JSON need not be strings, nor will they be examined in any search queries over the objects (with the exception of links which will be discussed shortly). In particular, the details will often store the necessary data to be conformant to a particular type, or convention. Arbitrary JSON can be stored with the exception of reserved strings mentioned below. The contents of an object’s details can be returned via a "getDetails" call.