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The schemaLocation attribute contains pairs of values: The first member of each pair is the namespace for which the second member is the hint describing where to find to an appropriate schema document. The schemaLocation attribute value consists of one or more pairs of URI references, separated by white space. The first member of each pair is a namespace name, and the second member of the pair is a hint describing where to find an appropriate schema document for that namespace. The presence of these hints does not require the processor to obtain or use the cited schema documents, and the processor is free to use other schemas obtained by any suitable means, or to use no schema at all.