HTML 5 Draft Standard - 30 July 2009 - Huihoo

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2 Common infrastructure
2.1 Terminology
This specification refers to both HTML and XML attributes and DOM attributes, often in the same
context. When it is not clear which is being referred to, they are referred to as content
attributes for HTML and XML attributes, and DOM attributes for those from the DOM.
Similarly, the term "properties" is used for both JavaScript object properties and CSS properties.
When these are ambiguous they are qualified as object properties and CSS properties
respectively.
Generally, when the specification states that a feature applies to the HTML syntax (page 781) or
the XHTML syntax (page 901), it also includes the other. When a feature specifically only applies
to one of the two languages, it is called out by explicitly stating that it does not apply to the
other format, as in "for HTML, ... (this does not apply to XHTML)".
This specification uses the term document to refer to any use of HTML, ranging from short
static documents to long essays or reports with rich multimedia, as well as to fully-fledged
interactive applications.
For simplicity, terms such as shown, displayed, and visible might sometimes be used when
referring to the way a document is rendered to the user. These terms are not meant to imply a
visual medium; they must be considered to apply to other media in equivalent ways.
When an algorithm B says to return to another algorithm A, it implies that A called B. Upon
returning to A, the implementation must continue from where it left off in calling B.
2.1.1 XML
To ease migration from HTML to XHTML, UAs conforming to this specification will place elements
in HTML in the http://www.w3.org/1999/xhtml namespace, at least for the purposes of the
DOM and CSS. The term "elements in the HTML namespace", or "HTML elements" for
short, when used in this specification, thus refers to both HTML and XHTML elements.
Unless otherwise stated, all elements defined or mentioned in this specification are in the
http://www.w3.org/1999/xhtml namespace, and all attributes defined or mentioned in this
specification have no namespace (they are in the per-element partition).
When an XML name, such as an attribute or element name, is referred to in the form
prefix:localName, as in xml:id or svg:rect, it refers to a name with the local name localName
and the namespace given by the prefix, as defined by the following table:
xml
html
http://www.w3.org/XML/1998/namespace
http://www.w3.org/1999/xhtml