notationDecl

notationDecl refers to a declaration within an XML document that specifies information about a notation. Notations are used to declare external entities that are not XML data. The notationDecl element is part of the XML DTD (Document Type Definition) syntax. It allows authors to indicate that certain entities within the XML document represent data that needs to be processed by a specific external application or in a particular format.

A notation declaration typically includes a name for the notation and an identifier. This identifier can be a public identifier, a system identifier, or both. The public identifier is a formal name for the notation, often used for interoperability, while the system identifier provides a URI or file path to locate the relevant information. The notationDecl can also specify that the notation is public or system.

For example, a notationDecl could be used to declare a notation for images, like JPEG or GIF, or for data formats like PDF. When an XML parser encounters an entity declared with such a notation, it knows that the entity's content is not XML and may need to be handled differently. The notationDecl itself does not contain the data but rather provides instructions on how to interpret or process it. This mechanism enables XML documents to reference and embed non-XML data in a structured way.