A JSON-LD Context
for the query. In an API, this will frequently be implicit. For example,
using json-rql as the body of a
http://example.com/my-api/v1/person/query might have the implicit context
of a Person (possibly found at
Specifies a Variable Expression or array of Variable Expressions that define [inline allowable value combinations]
specifies a pattern to match, or an array of patterns to match. Each can be a Subject, a Group, or another Query (a sub-query).