A space-separated list of datasources that an element's template will use for content generation. These can be either internal datasources such as rdf:bookmarks or a URL. The datasources attribute may be placed on most elements, although it will usually be found on trees and menu related elements. The element should have a template element as a child.
For RDF templates, the specified datasources are combined into a single composite datasource which holds the data from all of the datasources. This composite datasource is accesssible via a script through the database property.
For XML datasources, only one source is used, either the URL of an XML file or an anchor reference to another element within the same document. For instance, the reference '#data' refers to an element with the id 'data'.
If you plan on adding a datasource to an element but don't want one to be added right away, set this attribute to 'rdf:null'. This will make the element so that its contents can be generated from a datasource. Otherwise, you cannot add one later.
When the XUL document is contained on a remote web site, the datasources may only be loaded from the same domain as the document.