submits this Serql query and bbox binding

This Context is used to convert variable values from their abbreviated form to their fully expanded form. In this case, it is used for Sesame, who wants its variable binding values in ntriples format which is fully expanded.

It then applies this JSON-LD frame to format the response

to get the following framed JSON-LD

This gets replaced

Note that the frame changed the JSON-LD properties @id and @graph to id and graph respectively so that we could process them with PURE, which treats @ specially. The outermost label 'regions' comes from the id for the serql query, so that multiple queries can contribute to a collection of JSON.