H6

exceptions

Every document should have one, and only one <h1> element.

Normally H5 and H6 should not be used, and even H4 is rarely needed. If you feel the need for more than 3 or 4 headings, consider breaking your document into multiple hypertext nodes (i.e. put the text into more than one file and adjust the markup accordingly).

HTML defines six heading levels. These should be thought of as (roughly) analogous to Chapters, Sections, and Subsections, etc., in a conventional document. It should not be thought of as a way to get a particular graphic effect.

A heading element implies all the font changes, paragraph breaks before and after, and white space necessary to render the heading, but these changes are the responsibility of the browser software and the human reading the text, not the author. Further character emphasis or paragraph marks are neither required nor appropriate in HTML headings. Nor can heading appear other markup, except for BODY, BLOCKQUOTE (in the case that you are quoting another HTML fragment), and FORM.

For example, <b><h2>Summer Session Hours</h2></b> is illegal. <h2><b>Summer Session Hours</h2&gt;</b> is syntactially legal, but very bad form, since it is the prerogative of the reader and his/her browsing software to determine the appearance of heading text. (There are circumstances in which incorporating highlighting markup may be the only way to convey the meaning of the heading, but these are are rare and do not justify misuse of the markup rules).

Note that paragraphs following a header (ie those paragraphs that are 'part of the' section, must have p tags surrounding them, despite warnings in some style guides to the contrary.

The heading elements are H1, H2, H3, H4, H5, H6, with H1 being the highest level of heading. For example:

<H1>The Big Problems</H1>
<p>Here is some text. It should be considered "part of: heading 1</p>
<H2>Overview of the problems</H2>
<p>Here is some more text. It should be considered "part of:
'Overview of the problems', ie The first heading 2
<H3>Historical background to the problems</H3>
<p>Here is some more text. It should be considered "part of:
'Historical background', ie Heading3
<H2>Problem 1: The Economic situation</H2>

<p>Here is some more text. It should be considered "part of:
'Problem 1: The Economic Situation', ie the second Heading 2
</p>

NOTE

Although heading levels can be skipped (for example, from H1 to H3), this practice is discouraged as skipping header levels may produce unpredictable results when generating other representations from HTML.

Exceptions

Sometimes documents have a small quantity of preliminary material, such as a Journal title, volume, and issue number that is repeated from article to article. It is not always inappropriate to do something like

<h3>Scientific American<br>
January 1995</h3>
<h1>Ensuring the Longevity of Digital Documents</h1>

Similarly, repeated material at the tail of every document might appropriately be given the same kind of markup, even if it violates the general rule.

The key point is that h1 should identify the MAJOR HEADING for the document and that h2, h3, etc. should identify succesive 'nested' sections and subsections within a heading.

Content

• #PCDATA
• a -- Anchor; source and/or destination of a link
• b -- Bold text
• br -- Line break
• cite -- Name or title of cited work
• code -- Source code phrase
• em -- Emphasized phrase
• i -- Italic text
• img -- Image; icon, glyph or illustration
• kbd -- Keyboard phrase, e.g. user input
• samp -- Sample text or characters
• strong -- Strong emphasis
• tt -- Typewriter text
• var -- Variable phrase or substitutable

Tag Minimization

Open Tag: REQUIRED
Close Tag: REQUIRED

Parent Elements

• blockquote -- Quoted passage
• body -- Document body
• form -- Fill-out or data-entry form