[Name] fetchid [Required] false [Type] ECMAScript Left Hand Side Expression [Default Value] none [Valid Values] ECMAScript Variable [Description] 
An ECMAScript left hand side expression evaluating to a previously defined variable. The value of the attribute must receive an internally generated unique string identifier to be associated with the completion event. This identifier can be tested by the fetch completion event handler to distinguish among several outstanding fetch requests. If this attribute is not specified, the fetch identifier can be acquired from the fetch completion event. Every fetch request must receive a unique fetch identifier, even if the request is for the same URL. URI