The Grammar (HTML & XHTML: The Definitive Guide, 4th Edition)

A.2. The Grammar

The grammar is a composite of the HTML 4.01 and XHTML 1.0 standard tags and special extensions to the language as supported by the latest versions of Netscape Navigator and Microsoft's Internet Explorer.

The rules are in alphabetical order. The starting rule for an entire document is named html_document.

a_tag	::=	`<a>`
		{a_content }₀
		`</a>`
a_content[89] [89]a_content may not contain a_tags; you may not nest `<a>` tags within other `<a>` tags.	::=	heading
	\|	text
abbr_tag	::=	`<abbr>` text `</abbr>`
acronym_tag	::=	`<acronym>` text `</acronym>`
address_tag	::=	`<address>`
		{address_content }₀
		`</address>`
address_content	::=	p_tag
	\|	text
applet_content	::=	{`<param>`}₀
		body_content
applet_tag	::=	`<applet>`
		applet_content
		`</applet>`
b_tag	::=	`<b>` text `</b>`
basefont_tag	::=	`<basefont>`
		body_content
		`</basefont>`
bdo_tag	::=	`<bdo>` text `</bdo>`
big_tag	::=	`<big>` text `</big>`
blink_tag	::=	`<blink>` text `</blink>`
block	::=	{block_content }₀
block_content	::=	`<isindex>`
	\|	basefont_tag
	\|	blockquote_tag
	\|	center_tag
	\|	dir_tag
	\|	div_tag
	\|	dl_tag
	\|	form_tag
	\|	listing_tag
	\|	menu_tag
	\|	multicol_tag
	\|	nobr_tag
	\|	ol_tag
	\|	p_tag
	\|	pre_tag
	\|	table_tag
	\|	ul_tag
	\|	xmp_tag
blockquote_tag	::=	`<blockquote>`
		body_content
		`</blockquote>`
body_content	::=	`<bgsound>`
	\|	`<hr>`
	\|	address_tag
	\|	block
	\|	del_tag
	\|	heading
	\|	ins_tag
	\|	layer_tag
	\|	map_tag
	\|	marquee_tag
	\|	text
body_tag	::=	`<body>`
		{body_content }₀
		`</body>`
caption_tag	::=	`<caption>`
		body_content
		`</caption>`
center_tag	::=	`<center>`
		body_content
		`</center>`
cite_tag	::=	`<cite>` text `</cite>`
code_tag	::=	`<code>` text `</code>`
colgroup_content	::=	{`<col>`}₀
colgroup_tag	::=	`<colgroup>`
		colgroup_content
content_style	::=	abbr_tag
	\|	acronym_tag
	\|	cite_tag
	\|	code_tag
	\|	dfn_tag
	\|	em_tag
	\|	kbd_tag
	\|	q_tag
	\|	strong_tag
	\|	var_tag
dd_tag	::=	`<dd>`
		flow
		`</dd>`
del_tag	::=	`<del>`
		flow
		`</del>`
dfn_tag	::=	`<dfn>` text `</dfn>`
dir_tag[90] [90]The li_tag within the dir_tag may not contain any element found in a block.	::=	`<dir>`
		{ li_tag }
		`</dir>`
div_tag	::=	`<div>`
		body_content
		`</div>`
dl_content	::=	dt_tag dd_tag
dl_tag	::=	`<dl>`
		{dl_content }
		`</dl>`
dt_tag	::=	`<dt>`
		text
		`</dt>`
em_tag	::=	`<em>` text `</em>`
fieldset_tag	::=	`<fieldset>`
		[ legend_tag ]
		{ form_content }₀
		`</fieldset>`
flow	::=	{flow_content }₀
flow_content	::=	block
	\|	text
font_tag	::=	`<font>` style_text `</font>`
form_content[91] [91]form_content may not contain form_tags; you may not nest one `<form>` within another `<form>`.	::=	`<input>`
	\|	`<keygen>`
	\|	body_content
	\|	fieldset_tag
	\|	label_tag
	\|	select_tag
	\|	textarea_tag
form_tag	::=	`<form>`
		{form_content }₀
		`</form>`
frameset_content	::=	`<frame>`
	\|	noframes_tag
frameset_tag	::=	`<frameset>`
		{frameset_content }₀
		`</frameset>`
h1_tag	::=	`<h1>` text `</h1>`
h2_tag	::=	`<h2>` text `</h2>`
h3_tag	::=	`<h3>` text `</h3>`
h4_tag	::=	`<h4>` text `</h4>`
h5_tag	::=	`<h5>` text `</h5>`
h6_tag	::=	`<h6>` text `</h6>`
head_content	::=	`<base>`
	\|	`<isindex>`
	\|	`<link>`
	\|	`<meta>`
	\|	`<nextid>`
	\|	style_tag
	\|	title_tag
	\|	script_tag
head_tag	::=	`<head>`
		{head_content }₀
		`</head>`
heading	::=	h1_tag
	\|	h2_tag
	\|	h3_tag
	\|	h4_tag
	\|	h5_tag
	\|	h6_tag
html_content	::=	head_tag body_tag
	\|	head_tag frameset_tag
html_document	::=	html_tag
html_tag	::=	`<html>`
		html_content
		`</html>`
i_tag	::=	`<i>` text `</i>`
ilayer_tag	::=	`<ilayer>`
		body_content
		`</ilayer>`
ins_tag	::=	`<ins>`
		flow
		`</ins>`
kbd_tag	::=	`<kbd>` text `</kbd>`
label_content[92] [92]As with the `<form>` tag, you cannot imbed `<form>` or `<label>` tags within a `<label>` tag.	::=	`<input>`
	\|	body_content
	\|	select_tag
	\|	textarea_tag
label_tag	::=	`<label>`
		{label_content }₀
		`</form>`
layer_tag	::=	`<layer>`
		body_content
		`</layer>`
legend_tag	::=	`<legend>` text `</legend>`
li_tag	::=	`<li>`
		flow
		`</li>`
listing_tag	::=	`<listing>`
		literal_text
		`</listing>`
map_content	::=	{`<area>`}₀
map_tag	::=	`<map>`
		map_content
		`</map>`
marquee_tag	::=	`<marquee>`
		style_text
		`</marquee>`
menu_tag[93] [93]The li_tag within the menu_tag may not contain any element found in a block.	::=	`<menu>`
		{li_tag }₀
		`</menu>`
multicol_tag	::=	`<multicol>`
		body_content
		`</multicol>`
nobr_tag	::=	`<nobr>` text `</nobr>`
noembed_tag	::=	`<noembed>` text `</noembed>`
noframes_tag	::=	`<noframes>`
		{body_content }₀
		`</noframes>`
noscript_tag	::=	`<noscript>` text `</noscript>`
object_content	::=	{`<param>`}₀
		body_content
object_tag	::=	`<object>`
		object_content
		`</object>`
ol_tag	::=	`<ol>`
		{li_tag }
		`</ol>`
optgroup_tag	::=	`<optgroup>`
		{option_tag }₀
		`</optgroup>`
option_tag	::=	`<option>`
		plain_text
		`</option>`
p_tag	::=	`<p>`
		text
		`</p>`
physical_style	::=	b_tag
	\|	bdo_tag
	\|	big_tag
	\|	blink_tag
	\|	font_tag
	\|	i_tag
	\|	s_tag
	\|	small_tag
	\|	span_tag
	\|	strike_tag
	\|	sub_tag
	\|	sup_tag
	\|	tt_tag
	\|	u_tag
pre_content	::=	`<br>`
	\|	`<hr>`
	\|	a_tag
	\|	style_text
pre_tag	::=	`<pre>`
		{pre_content }₀
		`</pre>`
q_tag	::=	`<q>` text `</q>`
s_tag	::=	`<s>` text `</s>`
samp_tag	::=	`<samp>` text `</samp>`
script_tag[94] [94]A script_tag may be placed anywhere within an HTML document, without regard to syntactic rules.	::=	`<script>` plain_text `</script>`
select_content	::=	optgroup_tag
	\|	option_tag
select_tag	::=	`<select>`
		{select_content}₀
		`</select>`
server_tag[95] [95]A server_tag may be placed anywhere within an HTML document, without regard to syntactic rules.	::=	`<server>` plain_text `</server>`
small_tag	::=	`<small>` text `</small>`
span_tag	::=	`<span>` text `</span>`
strike_tag	::=	`<strike>` text `</strike>`
strong_tag	::=	`<strong>` text `</strong>`
style_tag	::=	`<style>` plain_text `</style>`
sub_tag	::=	`<sub>` text `</sub>`
sup_tag	::=	`<sup>` text `</sup>`
table_cell	::=	td_tag
	\|	th_tag
table_content	::=	`<tbody>`
	\|	`<tfoot>`
	\|	`<thead>`
	\|	tr_tag
table_tag	::=	`<table>`
		[caption_tag ]
		{colgroup_tag }₀
		{table_content }₀
		`</table>`
td_tag	::=	`<td>`
		body_content
		`</td>`
text	::=	{text_content }₀
text_content	::=	`<br>`
	\|	`<embed>`
	\|	`<iframe>`
	\|	`<img>`
	\|	`<spacer>`
	\|	`<wbr>`
	\|	a_tag
	\|	applet_tag
	\|	content_style
	\|	ilayer_tag
	\|	noembed_tag
	\|	noscript_tag
	\|	object_tag
	\|	plain_text
	\|	physical_style
textarea_tag	::=	`<textarea>` plain_text `</textarea>`
th_tag	::=	`<th>`
		body_content
		`</th>`
title_tag	::=	`<title>` plain_text `</title>`
tr_tag	::=	`<tr>`
		{table_cell }₀
		`</tr>`
tt_tag	::=	`<tt>` text `</tt>`
u_tag	::=	`<u>` text `</u>`
ul_tag	::=	`<ul>`
		{li_tag }
		`</ul>`
var_tag	::=	`<var>` text `</var>`
xmp_tag	::=	`<xmp>`
		literal_text
		`</xmp>`

[89]a_content may not contain a_tags; you may not nest <a> tags within other <a> tags.

[90]The li_tag within the dir_tag may not contain any element found in a block.

[91]form_content may not contain form_tags; you may not nest one <form> within another <form>.

[92]As with the <form> tag, you cannot imbed
<form> or <label> tags within a <label> tag.

[93]The li_tag within the menu_tag may not contain any element found in a block.

[94]A script_tag may be placed anywhere within an HTML document, without regard to syntactic rules.

[95]A server_tag may be placed anywhere within an HTML document, without regard to syntactic rules.