Extensible Metadata Platform (XMP) Specification - Adobe Partners

2
XMP Data Model
Property Values
Pirates of Penzance
dc:creator
"William Gilbert"
1
seq
2
"Arthur Sullivan"
ns:role
"lyricist"
ns:role
"composer"
Property qualifiers allow values to be extended without breaking existing usage. For example,
the ns:role qualifier in the diagram does not interfere with readers who simply want the
dc:creator names. An alternative would be to change dc:creator values to structures with name
and role fields, but that would confuse old software that expected to find a simple value.
The most common specific use of property qualifiers is for language alternative arrays (see
next section).
Language Alternatives
Language alternatives allow the text value of a property to be chosen based on a desired
language. Each item in a language alternative array is a simple text value, which must have a
language qualifier associated with it. The language qualifier is a property qualifier, as
described in the previous section. The qualifier name is xml:lang, and its value is a string that
conforms to RFC 3066 notation.
XMP uses the "x-default" language code to denote the default value for a language
alternative. It should be the first item in the array, so that generic RDF processors will also use
it as the default (according to the RDF default-is-first rule). The figure below shows an
example:
18 September 2005 XMP Specification