The secondary use is to record information that is useful to the end-user for obtaining more information about the resource directly. It is envisioned that data providers could provide descriptions of their services using this vocabulary. This might be done for each service by filling in values into a form. The vocabulary definition is organized as a list of fields , or concepts, which have associated values that describe attributes of the resource. Along with each field is a definition of the concept and, where applicable, the restrictions on the values it can have.
Restrictions can take the form of controlled vocabulary .
The vocabulary definition is divided into two categories. The first list addresses the primary use of the vocabulary, determining whether a query should be sent to the resource. That is, the resourse lists the constraints on the field value necessary to return at least one record matching a query that uses the field. In general, these two pieces of information can be used independently. The former piece indicates whether the service will properly use the part of the query referring to that field.