•Costs : need for human intervention and support of an infrastructure.  The DOI system operates on the basis that such costs are borne by the assigner of the DOI. 
–Number and metadata registration (maintenance of resolution destinations; declaration of metadata; validation of number syntax and of metadata; liaison with the IDF registry)
–Infrastructure (resolution service maintenance, scaling and further development; customer guidance and outreach; marketing; administration)
–Governance (common "rules of the road"; further development and support of the system)
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•The way in which these costs are recouped depends on the application.  
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How are costs met?
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