A source element in 1.1 has two string attributes: id and name. Can I ask for clarification of what these two attributes are for?
The id attribute acts like an HTML anchor. You can reference it from other places in the document. For example an <input> element refers to a <source> element using a URL fragment expression that consists of the id value.
<source id="somedata" name="anything" />
<input source="#somedata" />
The name attribute consists of XML name characters. They are user defined names that are independent of targetting or referencing.