OptionalextensionThe key of the file. Must be unique within both the Loader and the Text Cache.
OptionalshaderThe type of shader. Either fragment for a fragment shader, or vertex for a vertex shader. This is ignored if you load a shader bundle.
OptionalurlThe absolute or relative URL to load the file from.
OptionalxhrExtra XHR Settings specifically for this file.
The default file extension to use if no url is provided.