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In a previous life I was responsible for a metadata working group that created and incentivised the adoption of a new approach to metadata for the NZ compulsory education sector. Of note was the blend of "structured learning resource metadata" (based on IEE LOM and Dublin Core) and "user annotated" (or peer enhanced" metadata. Feel free to read over the final report and the vocabulary and numbering schema. For more on this user-peer approach see this child page.
The two approaches do not need to be mutually exclusive. Rather, they can play complimentary and supporting roles. Both could be useful for an area like research expertise, where whatever value list we provide will be insufficient for some researchers. But in most areas there will be little or no need for the user annotated or peer enhanced approach.
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