Entities

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Entities are shorthand references to data and data rules. When processed by an XML parser, they draw in and expand information.

• Internal general entities represent text and are defined within the DTD. External general entities represent text and are defined in files separate from the DTD document. Both are referenced in the DTD document using the SYSTEM parameter.

• External Parameter Entities reference data that becomes part of the DTD and is processed by the XML parser. Use SYSTEM to indicate a local document. Use PUBLIC if the document is in an offical listing of available, standardized entities such as can be found at www.schema.net.

• Non-Parsed Entities can include not just text, but also binary files, such as images, movies, pdf, etc... These entities are not processed by the XML parser. NDATA "content_information contains the notation to describe the non-parsed data. Unparsed entities do not have entity references, instead they are called through specially declared attributes. The contents of a notation can be, among other things, a MIME type or a URL to an external application that can handle the unparsed data.

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