          not defined in the JSON-LD @context with the understanding that any
          such properties will likely be unsupported and ignored by consuming
          implementations that use the standard JSON-LD algorithms. See the
          <a href="#extensibility">Extensibility</a> section for more information
          on handling extensions within Activity Streams 2.0 documents.
        </p>

        <p>
          JSON-LD uses the special <code>@context</code> property to define the
          <a href="h