FHIR: Nested extensions - hl7-fhir

Question

What is the correct representation of a multi-level FHIR extension?
<extension url="http://example.com/DataElement/researchAuth">
<extension url="http://example.com/DataElement/researchAuth.type">
<valueCode value="local" />
</extension>
<extension url="http://example.com/DataElement/researchAuth.flag>
<valueBoolean value="true" />
</extension>
</extension>
-- OR --
<extension url="http://example.com/DataElement/researchAuth">
<extension url="http://example.com/DataElement/researchAuth#type">
<valueCode value="local" />
</extension>
<extension url="http://example.com/DataElement/researchAuth#flag>
<valueBoolean value="true" />
</extension>
</extension>
In the StructureDefinition, should the URL for the sub-extensions be fully qualified (url: "http://example.com/DataElement/researchAuth#type") or just the name ("type") as here: http://hl7-fhir.github.io/extension-goal-relationship.html
Finally, is there an standard linkage between StructureDefinition.name and the sub-extension URL? I.e. the part after the # (type in http://example.com/DataElement/researchAuth#type) should match the name in the structure defition of the extension:
<StructureDefinition>
...
<element>
<path value="Extension" />
<name value="researchAuth" />
</element>
<element>
<path value="Extension.extension" />
<name value="researchAuth.type" />
</element>
...
</StructureDefinition>
Otherwise, how does one determine what the post # element is??
James's example adds to my confusion:
http://jamesagnew.github.io/hapi-fhir/doc_extensions.html
In the sub-extensions section, the "parent" is "http://example.com#parent" and the children are "http://example.com#ChildOne" and "http://example.com#ChildTwo" respectively.
I would expect only "http://example.com" for the parent extension (no # as it's the base extension defined at the URL). OR http://example.com#parent.ChildOne for the sub-extensions.

Answer 1

In DSTU 1, it would be the first approach. In DSTU 2, it would be this:
<extension url="http://example.com/DataElement/researchAuth">
<extension url="type">
<valueCode value="local" />
</extension>
<extension url="flag>
<valueBoolean value="true" />
</extension>
</extension>
That only holds for children of complex extensions. If you want to include an extension defined elsewhere inside another extension, you need to use the full URL.