The content of the value element must be zero or more <item> elements.
The content of each<item> element must match the String ::= Char* production. The list items might be empty or might duplicate other list items. The order of list items is significant. The Agent must preserve all characters in a list item, including the white space, exactly, as specified by the user. The Agent serializing the definition XML must, therefore, specify an xml:space="preserve" attribute on the value element.
See definition.