There are some Standards of fixed Prefixes that are written already in the RDF and RDF Schema (RDFS) Standard as well as XML Schema Definition (i.e. for the Datatypes) and the Web Ontology Language (OWL). On the other-hand if one does not know what a Prefix means or if there is a Prefix for some specific namespace there is specific Web Site dedicated for it where one can ask whether Prefixes exist or whether there is a namespace or the other way around [].

(cf. [])

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