The URLStream class provides low-level access to downloading data from URLs. In the runtime, the URLStream class includes a new event: httpResponseStatus. Unlike the httpStatus event, the httpResponseStatus event is delivered before any response data. The httpResponseStatus event (defined in the HTTPStatusEvent class) includes a responseURL property, which is the URL that the response was returned from, and a responseHeaders property, which is an array of URLRequestHeader objects representing the response headers that the response returned.