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The NOTATION attribute type provides a mechanism for associating an XML notation name with a particular element. In the declaration, a list of possible valid notations is given, like so:
<!ATTLIST picture src ENTITY #REQUIRED type NOTATION (bmp | gif | jpg) #REQUIRED >
Within the document, every <picture> element must have a type attribute that contains one of the notation names given in the list (bmp, gif, or jpg, in this example). When the document is parsed, the XML application can use the notation name to access additional information about the element type from the associated <!NOTATION> declaration.