The use of URLs in the XML technologies to reference external resources

Hi Folks,

The XML technologies use URLs to reference external resources. For example, XML Schema uses a URL in the <xs:include> and <xs:import> elements to reference other XML Schema documents.

The below list shows several XML technologies  and where they use URLs. Please let me know if I have missed any place where URLs are used in these technologies to reference external resources.  /Roger

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XML
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1. The <!ENTITY> external entity

2. The SYSTEM url in a <!DOCTYPE> declaration


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XML Schema
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1. The <xs:include> element

2. The <xs:import> element

3. The <xs:redefine> element

4. The xsi:schemaLocation attribute

5. The xsi:noNamespaceSchemaLocation attribute


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XSLT
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1. The document() function

2. The <xsl:include> element

3. The <xsl:import> element

4. <?xml-stylesheet> PI

5. The <xsl:import-schema> element

6. All the XPath functions


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XSLT/XPath
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1. The doc() function

2. The collection() function

3. The unparsed-text() function

4. The base-uri() function


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Schematron
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1. The <sch:include> element

2. All the XPath functions