This document allows you to navigate through the structure of the HTML 4.01 Transitional DTD

Element and attribute descriptions are extracted from RFC 1866.

For the latest information about HTML, see <URL: https://www.w3.org/hypertext/WWW/MarkUp/MarkUp.html>

SDA/ICADD: One to one mapping.

SDA/ICADD: Context-sensitive mapping.

SDA/ICADD: Generated text prefix.

SDA/ICADD: Generated text suffix.

SDA/ICADD: Suspend transform process.

The six heading elements, <H1> through <H6>, denote section headings. Although the order and occurrence of headings is not constrained by the HTML DTD, documents should not skip levels (for example, from H1 to H3), as converting such documents to other representations is often problematic.

Example of use:

    <H1>This is a heading</H1>
    Here is some text
    <H2>Second level heading</H2>
    Here is some more text.

Anchor; source and/or destination of a link Address, signature, or byline for document or passage Bold text Base context document Quoted passage Document body Line break Name or title of cited work Source code phrase Definition of term Directory list Definition list, or glossary Term in definition list Emphasized phrase Fill-out or data-entry form Heading, level 1 Heading, level 2 Heading, level 3 Heading, level 4 Heading, level 5 Heading, level 6 Document head Horizontal rule HyperText Markup Language Document Italic text Image; icon, glyph or illustration Form input datum Document is a searchable index Keyboard phrase, e.g. user input List item Link from this document Computer listing Menu list Generic meta-information Next ID to use for link name Ordered, or numbered list A selection option Paragraph Plain text passage Preformatted text Sample text or characters Selection of option(s) Strong emphasis An area for text input Title of document Typewriter text Unordered list Variable phrase or substitutable Example section

The <A> element indicates a hyperlink anchor. At least one of the NAME and HREF attributes should be present.

Gives the URI of the head anchor of a hyperlink.

Specifies methods to be used in accessing the destination, as a whitespace-separated list of names. The set of applicable names is a function of the scheme of the URI in the HREF attribute. For similar reasons as for the TITLE attribute, it may be useful to include the information in advance in the link. For example, the HTML user agent may chose a different rendering as a function of the methods allowed; for example, something that is searchable may get a different icon.

Gives the name of the anchor, and makes it available as a head of a hyperlink.

The REL attribute gives the relationship(s) described by the hyperlink. The value is a whitespace separated list of relationship names. The semantics of link relationships are not specified in this document.

Same as the REL attribute, but the semantics of the relationship are in the reverse direction. A link from A to B with REL="X" expresses the same relationship as a link from B to A with REV="X". An anchor may have both REL and REV attributes.

Suggests a title for the destination resource -- advisory only. The TITLE attribute may be used:

for display prior to accessing the destination resource, for example, as a margin note or on a small box while the mouse is over the anchor, or while the document is being loaded;
for resources that do not include a title, such as graphics, plain text and Gopher menus, for use as a window title.

Specifies a preferred, more persistent identifier for the head anchor of the hyperlink. The syntax and semantics of the URN attribute are not yet specified.

The <ADDRESS> element contains such information as address, signature and authorship, often at the beginning or end of the body of a document.

Example of use:

    <ADDRESS>
    Newsletter editor<BR>
    J.R. Brown<BR>
    JimquickPost News, Jimquick, CT 01234<BR>
    Tel (123) 456 7890
    </ADDRESS>

The <B> element indicates bold text. Where bold typography is unavailable, an alternative representation may be used.

The optional <BASE> element provides a base address for interpreting relative URLs when the document is read out of context The value of the HREF attribute must be an absolute URI.

The URL of the document.

The <BLOCKQUOTE> element contains text quoted from another source.

Example of use:

    I think the play ends
    <BLOCKQUOTE>
    <P>Soft you now, the fair Ophelia. Nymph, in thy orisons, be all
    my sins remembered.
    </BLOCKQUOTE>
    but I am not sure.

The <BODY> element contains the text flow of the document, including headings, paragraphs, lists, etc.

For example:

    <BODY>
    <h1>Important Stuff</h1>
    <p>Explanation about important stuff...
    </BODY>

The <BR> element specifies a line break between words. For example:

    <P> Pease porridge hot<BR>
    Pease porridge cold<BR>
    Pease porridge in the pot<BR>
    Nine days old.

The <CITE> element is used to indicate the title of a book or other citation.

The <CODE> element indicates an example of code, typically rendered in a mono-spaced font. The <CODE> element is intended for short words or phrases of code; the <PRE> block structuring element is more appropriate for multiple-line listings. For example:

    <p>The expression <code>x += 1</code>
    is short for <code>x = x + 1</code>.

Definition text of a term in a definition list.

The defining instance of a term.

The <DIR> element is similar to the <UL> element. It represents a list of short items, typically up to 20 characters each. Items in a directory list may be arranged in columns, typically 24 characters wide.

The content of a <DIR> element is a sequence of <LI> elements. Nested block elements are not allowed in the content of <DIR> elements. For example:

    <DIR>
    <LI>A-H<LI>I-M
    <LI>M-R<LI>S-Z
    </DIR>

Suggests that a compact rendering be used.

A definition list is a list of terms and corresponding definitions.

The content of a <DL> element is a sequence of <DT> elements and/or <DD> elements, usually in pairs. Multiple <DT> may be paired with a single <DD> element. Documents should not contain multiple consecutive <DD> elements.

Example of use:

    <DL>
    <DT>Term<DD>This is the definition of the first term.
    <DT>Term<DD>This is the definition of the second term.
    </DL>

The optional COMPACT attribute suggests that a compact rendering be used, because the list items are small and/or the entire list is large.

Definition term in a definition list.

The <EM> element indicates an emphasized phrase.

The date after which the document should be considered invalid. Semantics as in the HTTP specification.

A form is a template for a form data set and an associated method and action URI. A form data set is a sequence of name/value pair fields. The names are specified on the NAME attributes of form input elements, and the values are given initial values by various forms of markup and edited by the user. The resulting form data set is used to access an information service as a function of the action and method.

Forms elements can be mixed in with document structuring elements. For example, a <PRE> element may contain a <FORM> element, or a <FORM> element may contain lists which contain <INPUT> elements. This gives considerable flexibility in designing the layout of forms.

Specifies the action URI for the form. The action URI of a form defaults to the base URI of the document.

Specifies the media type used to encode the name/value pairs for transport, in case the protocol does not itself impose a format.

The default encoding for all forms is 'application/x-www-form-urlencoded'. A form data set is represented in this media type as follows:

The form field names and values are escaped: space characters are replaced by `+', and then reserved characters are escaped as per URL; that is, non-alphanumeric characters are replaced by `%HH', a percent sign and two hexadecimal digits representing the ASCII code of the character. Line breaks, as in multi-line text field values, are represented as CR LF pairs, i.e. `%0D%0A'.
The fields are listed in the order they appear in the document with the name separated from the value by `=' and the pairs separated from each other by `&'. Fields with null values may be omitted. In particular, unselected radio buttons and checkboxes should not appear in the encoded data, but hidden fields with VALUE attributes present should.

NOTE

The URI from a query form submission can be used in a normal anchor style hyperlink. Unfortunately, the use of the `&' character to separate form fields interacts with its use in SGML attribute values as an entity reference delimiter. For example, the URI `https://host/?x=1&y=2' must be written `<a href="https://host/?x=1&y=2">' or `<a href="https://host/?x=1&y=2">'.
HTTP server implementors, and in particular, CGI implementors are encouraged to support the use of `;' in place of `&' to save users the trouble of escaping `&' characters this way.

Selects a method of accessing the action URI. The set of applicable methods is a function of the scheme of the action URI of the form.

The head of an HTML document is an unordered collection of information about the document. For example:

    <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
    <HEAD>
    <TITLE>Introduction to HTML</TITLE>
    </HEAD>
    ...

The <HR> element is a divider between sections of text; typically a full width horizontal rule or equivalent graphic. For example:

    <HR>
    <ADDRESS>February 8, 1995, CERN<ADDRESS>
    <BODY>

The HTML document element consists of a head and a body, much like a memo or a mail message. The head contains the title and optional elements. The body is a text flow consisting of paragraphs, lists, and other elements.

The <I> element indicates italic text. Where italic typography is unavailable, an alternative representation may be used.

The <IMG> element refers to an image or icon via a hyperlink.

HTML user agents may process the value of the ALT attribute as an alternative to processing the image resource indicated by the SRC attribute.

NOTE: Some HTML user agents can process graphics linked via anchors, but not <IMG> graphics. If a graphic is essential, it should be referenced from an <A> element rather than an <IMG> element. If the graphic is not essential, then the <IMG> element is appropriate.

Examples of use:

    <IMG SRC="triangle.xbm" ALT="Warning:"> Be sure
    to read these instructions.

    <a href="https://machine/htbin/imagemap/sample">
    <IMG SRC="sample.xbm" ISMAP>
    </a>

Alignment of the image with respect to the text baseline.

`TOP' specifies that the top of the image aligns with the tallest item on the line containing the image.
`MIDDLE' specifies that the center of the image aligns with the baseline of the line containing the image.
`BOTTOM' specifies that the bottom of the image aligns with the baseline of the line containing the image.

Text to use in place of the referenced image resource, for example due to processing constraints or user preference.

Indicates an image map. If the ISMAP attribute is present on an <IMG> element, the <IMG> element must be contained in an <A> element with an HREF present. This construct represents a set of hyperlinks. The user can choose from the set by choosing a pixel of the image. The user agent computes the head URI by appending `?' and the x and y coordinates of the pixel to the URI given in the <A> element. For example, if a document contains:

   <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
   <head><title>ImageMap Example</title>
   <BASE HREF="https://host/index"></head>
   <body>
   <p> Choose any of these icons:<br>
   <a href="/cgi-bin/imagemap"><img ismap src="icons.gif"></a>

and the user chooses the upper-leftmost pixel, the chosen hyperlink is the one with the URI `https://host/cgi-bin/imagemap?0,0'.

Specifies the URI of the image resource.

The <INPUT> element represents a field for user input. The TYPE attribute discriminates between several variations of fields.

Valid for `TYPE=IMAGE'. Behaves the same as the ALIGN attribute for the <IMG> element.

Indicates that the initial state is on for CHECKBOX or RADIO input types.

Constrains the number of characters that can be entered into a text input field. If the value of MAXLENGTH is greater the the value of the SIZE attribute, the field should scroll appropriately. The default number of characters is unlimited.

Name for the form field corresponding to this element.

Specifies the amount of display space allocated to this input field according to its type. The default depends on the user agent.

Valid for `TYPE=IMAGE'. Attribute the same as the SRC attribute for the <IMG> element.

Defines the type of data the field accepts. Defaults to free text. Several types of fields can be defined with the type attribute:

CHECKBOX

Represents a boolean choice. A set of such elements with the same name represents an n-of-many choice field.

Example:

  <p>What flavors do you like?
  <input type=checkbox name=flavor value=vanilla>Vanilla<br>
  <input type=checkbox name=flavor value=strawberry>Strawberry<br>
  <input type=checkbox name=flavor value=chocolate checked>Chocolate<br>

HIDDEN

Represents a hidden field. The user does not interact with this field; instead, the VALUE attribute specifies the value of the field. The NAME and VALUE attributes are required.

Example:

    <input type=hidden name=context value="l2k3j4l2k3j4l2k3j4lk23">

IMAGE

Specifies an image resource to display, and allows input of two form fields: the x and y coordinate of a pixel chosen from the image. The names of the fields are the name of the field with `.x' and `.y' appended. `TYPE=IMAGE' implies `TYPE=SUBMIT' processing; that is, when a pixel is chosen, the form as a whole is submitted.

Example

    <p>Choose a point on the map:
    <input type=image name=point src="map.gif">

PASSWORD

A text field where the value is obscured as it is entered.

Example:

    <p>Name: <input name=login> Password: <input type=password name=passwd>

RADIO

Represents a boolean choice. A set of such elements with the same name represents a 1-of-many choice field.

Example:

    <p>Which is your favorite?
    <input type=radio name=flavor value=vanilla>Vanilla<br>
    <input type=radio name=flavor value=strawberry>Strawberry<br>
    <input type=radio name=flavor value=chocolate>Chocolate<br>

RESET

Represents an input option, typically a button, that instructs the user agent to reset the form's fields to their initial states. The VALUE attribute, if present, indicates a label for the input (button).

SUBMIT

Represents an input option, typically a button, that instructs the user agent to submit the form.

TEXT

Indicates a single line text entry field.

Example:

<p>Street Address: <input name=street><br>
Postal City code: <input name=city size=16 maxlength=16><br>
Zip Code: <input name=zip size=10 maxlength=10 value="99999-9999"><br>

The initial value of the field, or the value when checked for checkboxes and radio buttons.

When present indicates that this field is temporarily disabled. Browsers should show this by "greying it" out in some manner.

When present indicates that the field's initial value is in error in some way, e.g. because it is inconsistent with the values of other fields. Servers should include an explanatory error message with the form's text.

The <ISINDEX> element indicates that the user agent should allow the user to search an index by giving keywords.

The <KBD> element indicates text typed by a user, typically rendered in a mono-spaced font. This is commonly used in instruction manuals. For example:

Enter FIND IT to search the database.

A list item.

The <LINK> element represents a hyperlink. Any number of LINK elements may occur in the <HEAD> element of an HTML document. It has the same attributes as the <A> element.

The <LINK> element is typically used to indicate authorship, related indexes and glossaries, older or more recent versions, document hierarchy, associated resources such as style sheets, etc.

See anchors attributes for a description

of link's attributes.

See <XMP>.

The <MENU> element is a list of items with typically one line per item. The menu list style is typically more compact than the style of an unordered list.

The content of a <MENU> element is a sequence of <LI> elements. Nested block elements are not allowed in the content of <MENU> elements. For example:

    <MENU>
    <LI>First item in the list.
    <LI>Second item in the list.
    <LI>Third item in the list.
    </MENU>

Suggests that a compact rendering be used.

The <META> element is an extensible container for use in identifying specialized document meta-information. Meta-information has two main functions:

to provide a means to discover that the data set exists and how it might be obtained or accessed; and
to document the content, quality, and features of a data set, indicating its fitness for use.

Each <META> element specifies a name/value pair. If multiple META elements are provided with the same name, their combined contents-- concatenated as a comma-separated list--is the value associated with that name.

NOTE: The <META> element should not be used where a specific element, such as <TITLE>, would be more appropriate. Rather than a <META> element with a URI as the value of the CONTENT attribute, use a <LINK> element.

HTTP servers may read the content of the document <HEAD> to generate header fields corresponding to any elements defining a value for the attribute HTTP-EQUIV.

NOTE: The method by which the server extracts document meta-information is unspecified and not mandatory. The <META> element only provides an extensible mechanism for identifying and embedding document meta-information -- how it may be used is up to the individual server implementation and the HTML user agent.

Examples

If the document contains:

    <META HTTP-EQUIV="Expires"
          CONTENT="Tue, 04 Dec 1993 21:29:02 GMT">
    <meta http-equiv="Keywords" CONTENT="Fred">
    <META HTTP-EQUIV="Reply-to"
          content="fielding@ics.uci.edu (Roy Fielding)">
    <Meta Http-equiv="Keywords" CONTENT="Barney">

then the server may include the following header fields:

    Expires: Tue, 04 Dec 1993 21:29:02 GMT
    Keywords: Fred, Barney
    Reply-to: fielding@ics.uci.edu (Roy Fielding)

as part of the HTTP response to a `GET' or `HEAD' request for that document.

An HTTP server must not use the <META> element to form an HTTP response header unless the HTTP-EQUIV attribute is present.

An HTTP server may disregard any <META> elements that specify information controlled by the HTTP server, for example `Server', `Date', and `Last-modified'.

Specifies the name of the name/value pair. If not present, HTTP-EQUIV gives the name.

Binds the element to an HTTP header field. An HTTP server may use this information to process the document. In particular, it may include a header field in the responses to requests for this document: the header name is taken from the HTTP-EQUIV attribute value, and the header value is taken from the value of the CONTENT attribute. HTTP header names are not case sensitive.

Specifies the name of the name/value pair. If not present, HTTP-EQUIV gives the name.

The <NEXTID> element is included for historical reasons only. HTML documents should not contain <NEXTID> elements.

The <NEXTID> element gives a hint for the name to use for a new <A> element when editing an HTML document. It should be distinct from all NAME attribute values on <A> elements. For example:

   <NEXTID N=Z27>

The <OL> element represents an ordered list of items, sorted by sequence or order of importance. It is typically rendered as a numbered list.

The content of a <OL> element is a sequence of <LI> elements. For example:

    <OL>
    <LI>Click the Web button to open URI window.
    <LI>Enter the URI number in the text field of the Open URI
    window. The Web document you specified is displayed.
      <ol>
       <li>substep 1
       <li>substep 2
      </ol>
    <LI>Click highlighted text to move from one link to another.
    </OL>

Suggests that a compact rendering be used.

The Option element can only occur within a Select element. It represents one choice.

Indicates that this option is initially selected.

Indicates the value to be returned if this option is chosen. The field value defaults to the content of the <OPTION> element.

When present indicates that this option is temporarily disabled.

The <P> element indicates a paragraph.

Example of use:

    <H1>This Heading Precedes the Paragraph</H1>
    <P>This is the text of the first paragraph.
    <P>This is the text of the second paragraph. Although you do not
    need to start paragraphs on new lines, maintaining this
    convention facilitates document maintenance.</P>
    <P>This is the text of a third paragraph.</P>

<PLAINTEXT> is deprecated, and its use is strongly discouraged. All characters after the <PLAINTEXT> start-tag are data. Recognition of any HTML markup is disabled.

The <PRE> element represents a character cell block of text and is suitable for text that has been formatted for a monospaced font.

The <PRE> tag may be used with the optional WIDTH attribute. The WIDTH attribute specifies the maximum number of characters for a line and allows the HTML user agent to select a suitable font and indentation.

Within preformatted text:

Line breaks within the text are rendered as a move to the beginning of the next line.

NOTE

References to the "beginning of a new line" do not imply that the renderer is forbidden from using a constant left indent for rendering preformatted text. The left indent may be constrained by the width required.
Anchor elements and phrase markup may be used.

NOTE

Constraints on the processing of <PRE> content may limit or prevent the ability of the HTML user agent to faithfully render phrase markup.
Elements that define paragraph formatting (headings, address, etc.) must not be used.

NOTE

Some historical documents contain <P> tags in <PRE> elements. User agents are encouraged to treat this as a line break. A <P> tag followed by a newline character should produce only one line break, not a line break plus a blank line.
The horizontal tab character (code position 9 in the HTML document character set) must be interpreted as the smallest positive nonzero number of spaces which will leave the number of characters so far on the line as a multiple of 8. Documents should not contain tab characters, as they are not supported consistently.

Example of use:

<PRE>
Line 1.
       Line 2 is to the right of line 1.     <a href="abc">abc</a>
       Line 3 aligns with line 2.            <a href="def">def</a>
</PRE>

This attribute gives the maximum number of characters which will occur on a line. It allows the presentation system to select a suitable font and indentation. Where the WIDTH attribute is not recognized, it is recommended that a width of 80 be assumed. Where WIDTH is supported, it is recommended that at least widths of 40, 80 and 132 characters be presented optimally, with other widths being rounded up.

The <SAMP> element indicates a sequence of literal characters, typically rendered in a mono-spaced font. For example:

The only word containing the letters mt is dreamt.

The <SELECT> element constrains the form field to an enumerated list of values. The values are given in <OPTION> elements.

Example:

    <SELECT NAME="flavor">
    <OPTION>Vanilla
    <OPTION>Strawberry
    <OPTION value="RumRasin">Rum and Raisin
    <OPTION selected>Peach and Orange
    </SELECT>

The initial state has the first option selected, unless a SELECTED attribute is present on any of the <OPTION> elements.

Indicates that more than one option may be included in the value.

Specifies the name of the form field.

Specifies the number of visible items. Select fields of size one are typically pop-down menus, whereas select fields with size greater than one are typically lists.

The ERROR attribute can be used to indicate that the initial selection is in error in some way, e.g. because it is inconsistent with the values of other fields.

The STRIKE element indicates "strike out" text, as in a legal document. This tag is not widely supported.

The <STRONG> element indicates strong emphasis, typically rendered in bold. For example:

<strong>STOP</strong>, or I'll say "<strong>STOP</strong>" again!

The <TEXTAREA> element represents a multi-line text field in a Form.

Example:

    <TEXTAREA NAME="address" ROWS=6 COLS=64>
    HaL Computer Systems
    1315 Dell Avenue
    Campbell, California 95008
    </TEXTAREA>

The content of the <TEXTAREA> element is the field's initial value.

The number of visible columns to display for the text area, in characters.

Specifies the name of the form field.

The number of visible rows to display for the text area, in characters.

Every HTML document must contain a <TITLE> element.

The title should identify the contents of the document in a global context. A short title, such as "Introduction" may be meaningless out of context. A title such as "Introduction to HTML Elements" is more appropriate.

NOTE

The length of a title is not limited; however, long titles may be truncated in some applications. To minimize this possibility, titles should be fewer than 64 characters.

A user agent may display the title of a document in a history list or as a label for the window displaying the document. This differs from headings, which are typically displayed within the body text flow.

The <TT> element indicates teletype (monospaced) text. Where a teletype font is unavailable, an alternative representation may be used.

The <UL> represents a list of items -- typically rendered as a bulleted list.

The content of a <UL> element is a sequence of <LI> elements. For example:

    <UL>
    <LI>First list item
    <LI>Second list item
     <p>second paragraph of second item
    <LI>Third list item
    </UL>

Suggests that a compact rendering be used.

The <VAR> element indicates a placeholder variable, typically rendered as italic. For example:

  Type <SAMP>html-check <VAR>file</VAR> | more</SAMP>
  to check <VAR>file</VAR> for markup errors.

The <XMP> and <LISTING> elements are similar to the <PRE> element, but they have a different syntax. Their content is declared as CDATA, which means that no markup except the end-tag open delimiter-in-context is recognized.

NOTE: In a previous draft of the HTML specification, the syntax of <XMP> and <LISTING> elements allowed closing tags to be treated as data characters, as long as the tag name was not <XMP> or <LISTING>, respectively.

Since CDATA declared content has a number of unfortunate interactions with processing techniques and tends to be used and implemented inconsistently, HTML documents should not contain <XMP> nor <LISTING> elements -- the <PRE> tag is more expressive and more consistently supported.

The <LISTING> element should be rendered so that at least 132 characters fit on a line. The <XMP> element should be rendered so that at least 80 characters fit on a line but is otherwise identical to the <LISTING> element.

NOTE: In a previous draft, HTML included a <PLAINTEXT> element that is similar to the <LISTING> element, except that there is no closing tag: all characters after the <PLAINTEXT> start-tag are data.