Is there known URI scheme or URN namespace for Unicode characters?
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I need to reference to a Unicode character with a URI. Following IANA references list multiple schemes and namespaces but do not mention anything about identifiers for the Unicode characters. Does anyone know if something like this exists already?

 - http://www.iana.org/assignments/uri-schemes.html
 - http://www.iana.org/assignments/urn-namespaces/urn-namespaces.xml

I hoped to find something like 

 - <code>unicode://U+0394</code>
 - <code>urn:unicode://0394</code>
 - <code>http://unicode.org/unicode/0394</code>

for the greek capital letter delta Δ.

If someone wonders, this is for a semantic web like application that uses URIs as identifiers for concepts, including concepts of the Unicode characters.