 Concerns
 Effects of proliferation
Prolifieration of URI schemes works against interoperability
Consistency of file: URI scheme
This is a misunderstood URI scheme, where the misunderstandings result in apparent inconsistencies.
Application constraints on scheme types
Some applications or protocols may constrain allowable URI schemes, which appears to go against the
idea of universality.
URI form constraints
Some applications or protocols may constrain the form of allowable URI: e.g. no relative form or fragment
identifiers allowed.
Internationalization/
Unicode support
URIs and QNames
Some XML applications, notable XML namespaces, adopt the idea of a base URI that references a collection
of resources, and sub-URIs (path-children or fragment
identifiers) that refer to members of the collection. This combination of base URI and local name
is referred to as a QName.
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