Choose some data stream to upload: file, camera phone photo, video, audio recording, etc.
ref attribute identifies part of model that holds the Base-64 encoded contents
mediatype attribute specifies the types of files the user can select
filename element identifies part of model that holds the filename
mediatype element identifies part of model that holds the MIME type of the file
Can submit as multipart/related rather than just Base-64 encoding everything
<upload ref="patch" mediatype="text/*">
<label>Select image:</label>
<filename ref="@name" />
<mediatype ref="@mimetype" />
</upload>