to the element with id="bar". Graphical Web browsers typically scroll to position pages so that the top of the element identified by the fragment id is aligned with the top of the viewport; thus fragment identifiers are often used in tables of content and in permalinks. The appearance of the identified element can be changed through the :target CSS pseudoclass; Wikipedia uses this to highlight the selected reference. Notably CSS display: block can be used to show content only if it is the target, and otherwise hidden by display: none. The deprecated name attribute (allowed only for some elements) had a similar purpose in now obsolete browsers. If present name and id must be identical. In all XML document types including XHTML fragments corresponding to an xml:id or similar id attributes follow the Name-syntax and begin with a letter, underscore, or colon. Notably they cannot begin with a digit or hyphen. xml:id is one of the few generic XML attributes, e.g., xml:lang, which can be used without explicitly declaring a namespace. In XHTML id has to be used, because XHTML was specified before xml:id existed. In XML applications, fragment identifiers in a certain syntax can be XPointers; for example, the fragment identifier in the URI http://www.example.org/foo.xml#xpointer(//Rube) refers to all XML elements named "Rube" in the document identified by the URI http://www.example.org/foo.xml. An XPointer processor, given that URI, would obtain a representation of the document (such as by requesting it from the Internet) and would return a representation of the document's "Rube" elements. In RDF vocabularies, such as RDFS, OWL, or SKOS, fragment identifiers are used to identify resources in the same XML Namespace, but are not necessarily corresponding to a specific part of a document. For example, http://www.w3.org/2004/02/skos/core#broader identifies the concept "broader" in SKOS Core vocabulary, but it does not refer to a specific part of the resource identified by http://www.w3.org/2004/02/skos/core, a complete RDF file in which semantics of this specific concept is declared, along with other concepts in the same vocabulary. In URIs for MIME text/plain documents RFC 5147 specifies a fragment identifier for the character and line positions and ranges within the document using the keywords "char" and "line". Browser support seems lacking. The following example identifies lines 11 through 20 of a text document: http://example.com/document.txt#line=10,20 In URIs for MIME text/csv documents, RFC 7111 specifies a fragment identifier as a selector for rows, columns, and cells using the