|W3C XML Schema approach||NVDL approach|
|All possible usages of vocabulary has to be known in advance.||Vocabularies can be combined on demand.|
|“Early binding” between namespaces||“Late binding” between namespaces|
|“Tightly” coupled schemas||“Loosely” coupled schemas|
|Driven by authors of “base” vocabularies and their schemas.||Driven by users and needs of their compound documents.|
Best practice: Create single namespace schemas for individual XML languages and move any compound language definitions to a separate layer (NVDL).