Extended Metadata Schema Properties
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.. autosummary::
   :toctree: generated

Overview
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'Extended' metadata allows some customisation by Registration Agencies. All properties must be used without variation. Requirements, constraints, and format must be enforced. Controlled lists, however, may be modified. 

Registration agencies may:

1. Add existing controlled list schemas from other sources, so long as they are human and machine-readable with a single page per value. 
2. Build new controlled list schemas, so long as they are human and machine-readable with a single page per value. 

Note that not all existing schemes provide a URI for each term, in which case Registration Agencies will need to build and publish their own lists. 

All non-canonical schemas or controlled lists must be registered with the Registration Authority and published to a vocabulary service.

Contents
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.. toctree::

   subjects
   spatialCoverages
   traditionalKnowledge