`limited` specifies how requests are handled for a Limited priority level. This field must be non-empty if and only if `type` is `"Limited"`.

`type` indicates whether this priority level is subject to limitation on request execution. A value of `"Exempt"` means that requests of this priority level are not subject to a limit (and thus are never queued) and do not detract from the capacity made available to other priority levels. A value of `"Limited"` means that (a) requests of this priority level _are_ subject to limits and (b) some of the server's limited capacity is made available exclusively to this priority level. Required.