# 8. XHTML Structural Module

Contents

This section is normative.

This module defines all of the basic text container elements, attributes, and their content models that are structural in nature.

Element | Attributes | Content Model
--- | --- | ---
address | Common | (PCDATA | Text)*
blockcode | Common | (PCDATA | Text | Heading | Structural | List)*
blockquote | Common | (PCDATA | Text | Heading | Structural | List)*
div | Common | (PCDATA | Flow)*
h | Common | (PCDATA | Text)*
h1 | Common | (PCDATA | Text)*
h2 | Common | (PCDATA | Text)*
h3 | Common | (PCDATA | Text)*
h4 | Common | (PCDATA | Text)*
h5 | Common | (PCDATA | Text)*
h6 | Common | (PCDATA | Text)*
p | Common | (PCDATA | Text | List | blockcode | blockquote | pre | table )*
pre | Common | (PCDATA | Text)*
section | Common | (PCDATA | Flow)*
separator | Common | EMPTY

The content model for this module defines some content sets:

Heading
  h | h1 | h2 | h3 | h4 | h5 | h6
Structural
  address | blockcode | blockquote | div | link | List | meta | p | pre | handler | section | separator | table
Flow
  Heading | Structural | Text

Implementation: RELAX NG

## 8.1. The address element

The address element may be used by authors to supply contact information for a document or a major part of a document such as a form.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

Example

    <address href="mailto:webmaster@example.net">Webmaster</address>

## 8.2. The blockcode element

This element indicates that its contents are a block of "code" (see the code element). This element is similar to the pre element, in that whitespace in the enclosed text has semantic relevance. As a result, the default value of the layout attribute is `relevant`.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

Example of a code fragment:

    <blockcode class="Perl">
    sub squareFn {
        my $var = shift;

        return $var * $var ;
    }
    </blockcode>

Here is how this might be rendered:

    sub squareFn {
        my $var = shift;

        return $var * $var ;
    }

## 8.3. The blockquote element

This element designates a block of quoted text.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

An excerpt from 'The Two Towers', by J.R.R. Tolkien, as a blockquote

    <blockquote cite="http://www.example.com/tolkien/twotowers.html">
    <p>They went in single file, running like hounds on a strong scent,
    and an eager light was in their eyes. Nearly due west the broad
    swath of the marching Orcs tramped its ugly slot; the sweet grass
    of Rohan had been bruised and blackened as they passed.</p>
    </blockquote>

## 8.4. The div element

The div element, in conjunction with the id, class and role attributes, offers a generic mechanism for adding extra structure to documents. This element defines no presentational idioms on the content. Thus, authors may use this element in conjunction with style sheets, the xml:lang attribute, etc., to tailor XHTML to their own needs and tastes.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

For example, suppose you wish to make a presentation in XHTML, where each slide is enclosed in a separate element. You could use a div element, with a class of `slide`:

div with a class of slide

    <body>
        <h>The meaning of life</h>
        <p>By Huntington B. Snark</p>
        <div class="slide">
            <h>What do I mean by "life"</h>
            <p>....</p>
        </div>
        <div class="slide">
            <h>What do I mean by "mean"?</h>
            ...
        </div>
        ...
    </body>

## 8.5. The heading elements

A heading element briefly describes the topic of the section it introduces. Heading information may be used by user agents, for example, to construct a table of contents for a document automatically.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

There are two styles of headings in XHTML: the numbered versions h1, h2 etc., and the structured version h, which is used in combination with the section element.

There are six levels of numbered headings in XHTML with h1 as the most important and h6 as the least.

Structured headings use the single h element, in combination with the section element to indicate the structure of the document, and the nesting of the sections indicates the importance of the heading. The heading for the section is the one that is a child of the section element.

Example

    <body>
    <h>This is a top level heading</h>
    <p>....</p>
    <section>
        <p>....</p>
        <h>This is a second-level heading</h>
        <p>....</p>
        <h>This is another second-level heading</h>
        <p>....</p>
    </section>
    <section>
        <p>....</p>
        <h>This is another second-level heading</h>
        <p>....</p>
        <section>
            <h>This is a third-level heading</h>
            <p>....</p>
        </section>
    </section>
    </body>

Sample style sheet for section levels

    h {font-family: sans-serif; font-weight: bold; font-size: 200%}
    section h {font-size: 150%} /* A second-level heading */
    section section h {font-size: 120%} /* A third-level heading */

Numbered sections and references
XHTML does not itself cause section numbers to be generated from headings. Style sheet languages such as CSS however allow authors to control the generation of section numbers.

The practice of skipping heading levels is considered to be bad practice. The series `h1 h2 h1` is acceptable, while `h1 h3 h1` is not, since the heading level `h2` has been skipped.

## 8.6. The p element

The p element represents a paragraph.

In comparison with earlier versions of HTML, where a paragraph could only contain inline text, XHTML2's paragraphs represent the conceptual idea of a paragraph, and so may contain lists, blockquotes, pre's and tables as well as inline text. Note however that they may not contain directly nested p elements.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

Example

    <p>Payment options include:
    <ul>
    <li>cash</li>
    <li>credit card</li>
    <li>luncheon vouchers.</li>
    </ul>
    </p>

## 8.7. The pre element

The pre element indicates that whitespace in the enclosed text has semantic relevance. As such, the default value of the layout attribute is relevant.

Note that all elements in the XHTML family preserve their whitespace in the document, which is only removed on rendering, via a style sheet, according to the rules of CSS [CSS3-TEXT]. This means that in principle any elements may preserve or collapse whitespace on rendering, under control of a style sheet.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

A bad poem where whitespace matters

    <pre>
                    If
                  I   had
               any      talent
                  I   would
                   be a

                   poet
    </pre>

Here is how this might be rendered:

                    If
                  I   had
               any      talent
                  I   would
                   be a

                   poet

Note that while historically one use of the pre element has been as a container for source code, the blockcode element is intended for that.

## 8.8. The section element

The section element, in conjunction with the h element, offers a mechanism for structuring documents into sections. This element defines content to be block-level but imposes no other presentational idioms on the content, which may otherwise be controlled from a style sheet.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

By representing the structure of documents explicitly using the section and h elements gives the author greater control over presentation possibilities than the traditional implicit structuring using numbered levels of headings. For instance, it is then possible to indicate the nesting of sections by causing a border to be displayed to the left of sections.

Example

    <body>
    <h>Events</h>
    <section>
        <h>Introduction</h>
        <p>....</p>
        <h>Specifying events</h>
        <p>...</p>
        <section>
            <h>Attaching events to the handler</h>
            <p>...</p>
        </section>
        <section>
            <h>Attaching events to the listener</h>
            <p>...</p>
        </section>
        <section>
            <h>Specifying the binding elsewhere</h>
            <p>...</p>
        </section>
    </section>
    </body>

## 8.9. The separator element

The separator element separates parts of the document from each other.

Attributes

The Common collection
  A collection of other attribute collections, including: Bi-directional, Core, Edit, Embedding, Events, Forms, Hypertext, I18N, Map, and Metainformation.

Example

    <p>This is some lead in text</p>
    <separator />
    <p>This is some additional, but separate text.</p>

Example

    <nl>
    <label>Navigation</label>
    <li href="/">Home</li>
    <li><separator/></li>
    <li href="prev">Previous</li>
    <li href="..">Up</li>
    <li href="next">Next</li>
    </nl>

## 8.10. Issues

[XHTML2] How are UAs to interpret <h> and <hx> elements? PR #7820
State: Open
Resolution: None
User: None

Notes:

[XHTML2] How are UAs to interpret <h> and <hx> elements? PR #7830
State: Open
Resolution: None
User: None

Notes:

block@kind vs elt@structure PR #7874
State: Open
Resolution: None
User: None

Notes:

redundant content model PR #7875
State: Open
Resolution: None
User: None

Notes:
Agreed - should change these to be Flow.

headings -- numbered vs bare PR #7877
State: Open
Resolution: None
User: None

Notes:
You are correct - there is nothing but good taste to prevent people doing silly things. However, we need better wording to clarify that the content model does indeed support bad taste.