dojox.io.xhrMultiPart constructs multi-part mime XHR requests.
dojox.io.xhrMultiPart is useful when wanting multi-part requests but not using a form with a file input. Note that it does not allow you to send files from local disks -- a form with a file input is required for that use case. xhrMultipart is not useful in that use case.
TODO: how to use the component/class/method
// your code