Several of the examples use STC which requires stc-v1.30.xsd and xlink.xsd.
Note: The samples above were created to be compliant only with the VOResource schema and the above extensions. These would have a different wrapping or "root" element (namely, the <ri:Resource> element) when used as part of a Registry service, the details depending on the type of message; see the RI spec for specifics. (I'll try to update these with Registry-specific versions to avoid confusion --rp)
How to Create a New Extension Schema
The recommended process for creating a new VOResource extension is outlined in a presentation during InterOpSep2007: