Core Attribute Collection

Attributes in this Collection

id [ type ID ]

A unique identifier for the element

class [ type NMTOKENS ]

One or more space separated classes

title [ type Text ]

Descriptive title for the element (in some user agents this may appear as a "tooltip" when the mouse hovers over the element)

xmlns [ type URI - #FIXED 'http://www.w3.org/1999/xhtml' ]

XML namespace

style [ type CDATA ], from the Style Attribute Module (deprecated)

Element-specific styles

Where to Use Attributes in this Collection

• The id attribute may be used on most elements in the Element Index - all except: base, head, html, meta, title. It is #REQUIRED on the map element.
  Note: Although the id attribute is seemingly permitted by the *XHTML 1.1 Structure Module DTD on the html and head elements, its presence on these elements currently causes a page to fail W3C Validation and so they are not considered valid in this reference.
• The class attribute may be used on most elements in the Element Index - all except: base, head, html, meta, param, script, style, title.
• The title attribute may be used on most elements in the Element Index - all except: base, head, html, meta, param, script, title.
• The xmlns attribute may be used on any element in the Element Index. Despite being #FIXED rather than #REQUIRED in the DTD, the xmlns attribute is compulsory on the html element in order for a document to pass W3C Validation.
• The style attribute may be used on most elements in the Element Index - all except: base, head, html, meta, param, script, style, title.

Description

The Core Attribute Collection contains attributes used by the majority of XHTML 1.1 elements. Usually these attributes are optional, with the exceptions that the id attribute is #REQUIRED on the map element and that the #FIXED xmlns attribute is compulsory on the html element for an XHTML 1.1 document to successfully pass W3C Validation.

The style attribute is declared by the deprecated Style Attribute Module and so should be avoided in new code. Sometimes this attribute is put in its own separate Collection (for example in the W3C *W3C - XHTML Modularisation 1.1 - Attribute Collections page) but within the DTD itself it is added to the Core Attribute Collection, via the entity Core.extra.attrib - see *Style Attribute Module DTD for more information.

The Style Attribute Module is selected in the default DTD used on this site and so this module has been documented, despite being deprecated.

A Word on the xml:space Attribute

The xml:space attribute (see: *XML 1.0 White Space Handling) is included as part of the *Core Attribute Collection at the W3C (Prose Specification) and is given an *XML 1.0 default declaration of #FIXED 'preserve' in the *XHTML Common Attributes DTD. In the DTD, it is also similarly declared on the script and style elements.

Due to current inconsistencies between the Prose Specification, the DTD and the behaviour of the *W3C Validator I am not going to mention the xml:space attribute any further on this site (except for a mention in XHTML 1.1 Inconsistencies). Since the DTD allows only a value of "preserve" (although the prose says otherwise!), there seems little point in adding it to an element in any case.