14 September 2005 XMP Specification XMP Data Model Schemas and Namespaces 2 In the diagrams that illustrate the data model in this chapter, the top or root of the metadata tree is the resource—that is, the document or component to which the metadata applies. NOTE: The top level nodes in these illustrations have names simply for the sake of clarity for the reader. Within the XMP data model the resource need not have a formal name. NOTE: All property, structure field, and qualifier names in XMP must be legal XML qualified names. That is, they must be well formed XML names and in an XML namespace. IMPORTANT: To work properly with RDF, all XML namespaceURIs used in XMP must be terminated with "/" or "#". See , “Namespace termination” on page 29 for details. Schemas and Namespaces An XMP Schema is a set of top level property names in a common XML namespace, along with data type and descriptive information. Typically, an XMP schema contains properties that are relevant for particular types of documents or for certain stages of a workflow. Chapter 4, “XMP Schemas”, defines a set of standard metadata schemas and explains how to define new schemas. NOTE: The term “XMP Schema” used here to clearly distinguish this concept from other uses of the term “schema”, and notably from the W3C XML Schema language. An XMP Schema is typically less formal, defined by documentation instead of a machine readable schema file. An XMP Schema is identified by its XML namespace URI. The use of namespaces avoids conflict between properties in different schemas that have the same name but different meanings. For example, two independently designed schemas might have a Creator property: in one, it might mean the person who created a resource in another, the application used to create the resource. The namespace URI for an XMP Schema must obey the rules for XML 1.1 namespaces. In addition, to operate well with RDF it must end with a ‘/’ or ‘#’ character. (See “Namespace URI termination” on page 29) The URI might or might not actually locate a resource such as a web page. XMP places no significance on the scheme or components of the namespace URI. Moby Dick Author Date Written "1851" "Herman Melville"