RFC1866 - Hypertext Markup Language - 2.0(2)

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>

5.6.2. Ordered List: OL

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>

5.6.3. Directory List: DIR

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>

5.6.4. Menu List: MENU

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>

5.6.5. Definition List: DL, DT, DD

A definition list is a list of terms and corresponding definitions.
Definition lists are typically formatted with the term flush-left and
the definition, formatted paragraph style, indented after the term.

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>

If the DT term does not fit in the DT column (typically one third of
the display area), it may be extended across the page with the DD
section moved to the next line, or it may be wrapped onto successive
lines of the left hand column.

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

Unless the COMPACT attribute is present, an HTML user agent may leave
white space between successive DT, DD pairs. The COMPACT attribute
may also reduce the width of the left-hand (DT) column.

<DL COMPACT>
<DT>Term<DD>This is the first definition in compact format.
<DT>Term<DD>This is the second definition in compact format.
</DL>

5.7. Phrase Markup

Phrases may be marked up according to idiomatic usage, typographic
appearance, or for use as hyperlink anchors.

User agents must render highlighted phrases distinctly from plain
text. Additionally, <EM> content must be rendered as distinct from
<STRONG> content, and <B> content must rendered as distinct from <I>
content.

Phrase elements may be nested within the content of other phrase
elements; however, HTML user agents may render nested phrase elements

indistinctly from non-nested elements:

plain <B>bold <I>italic</I></B> may be rendered
the same as plain <B>bold </B><I>italic</I>

5.7.1. Idiomatic Elements

Phrases may be marked up to indicate certain idioms.

NOTE - User agents may support the <DFN> element, not included in
this specification, as it has been deployed to some extent. It is
used to indicate the defining instance of a term, and it is
typically rendered in italic or bold italic.

5.7.1.1. Citation: CITE

The <CITE> element is used to indicate the title of a book or
other citation. It is typically rendered as italics. For example:

He just couldn't get enough of <cite>The Grapes of Wrath</cite>.

5.7.1.2. Code: CODE

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 (5.5.2, "Preformatted Text: PRE") is more appropriate
for multiple-line listings. For example:

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

5.7.1.3. Emphasis: EM

The <EM> element indicates an emphasized phrase, typically
rendered as italics. For example:

A singular subject <em>always</em> takes a singular verb.

5.7.1.4. Keyboard: KBD

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 <kbd>FIND IT</kbd> to search the database.

5.7.1.5. Sample: SAMP

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

The only word containing the letters <samp>mt</samp> is dreamt.

5.7.1.6. Strong Emphasis: STRONG

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

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

5.7.1.7. Variable: VAR

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.

5.7.2. Typographic Elements

Typographic elements are used to specify the format of marked
text.

Typical renderings for idiomatic elements may vary between user
agents. If a specific rendering is necessary -- for example, when
referring to a specific text attribute as in "The italic parts are
mandatory" -- a typographic element can be used to ensure that the
intended typography is used where possible.

NOTE - User agents may support some typographic elements not
included in this specification, as they have been deployed to some
extent. The <STRIKE> element indicates horizontal line through the
characters, and the <U> element indicates an underline.

5.7.2.1. Bold: B

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

5.7.2.2. Italic: I

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

5.7.2.3. Teletype: TT

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

5.7.3. Anchor: A

The <A> element indicates a hyperlink anchor (see 7, "Hyperlinks").
At least one of the NAME and HREF attributes should be present.
Attributes of the <A> element:

HREF
gives the URI of the head anchor of a hyperlink.

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

TITLE
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.

REL
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.

REV
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.

URN
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.

METHODS
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.

5.8. Line Break: BR

The <BR> element specifies a line break between words (see 6,
"Characters, Words, and Paragraphs"). For example:

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

5.9. Horizontal Rule: HR

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>

5.10. Image: IMG

The <IMG> element refers to an image or icon via a hyperlink (see
7.3, "Simultaneous Presentation of Image Resources").

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.

Attributes of the <IMG> element:

ALIGN
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.

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

ISMAP
indicates an image map (see 7.6, "Image Maps").

SRC
specifies the URI of the image resource.

NOTE - In practice, the media types of image
resources are limited to a few raster graphic
formats: typically `image/gif', `image/jpeg'. In
particular, `text/html' resources are not
intended to be used as image resources.

Examples of use:

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

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

6. Characters, Words, and Paragraphs

An HTML user agent should present the body of an HTML document as a
collection of typeset paragraphs and preformatted text. Except for
preformatted elements (<PRE>, <XMP>, <LISTING>, <TEXTAREA>), each
block structuring element is regarded as a paragraph by taking the

data characters in its content and the content of its descendant
elements, concatenating them, and splitting the result into words,
separated by space, tab, or record end characters (and perhaps hyphen
characters). The sequence of words is typeset as a paragraph by
breaking it into lines.

6.1. The HTML Document Character Set

The document character set specified in 9.5, "SGML Declaration for
HTML" must be supported by HTML user agents. It includes the graphic
characters of Latin Alphabet No. 1, or simply Latin-1. Latin-1
comprises 191 graphic characters, including the alphabets of most
Western European languages.

NOTE - Use of the non-breaking space and soft hyphen indicator
characters is discouraged because support for them is not widely
deployed.

NOTE - To support non-western writing systems, a larger character
repertoire will be specified in a future version of HTML. The
document character set will be [ISO-10646], or some subset that
agrees with [ISO-10646]; in particular, all numeric character
references must use code positions assigned by [ISO-10646].

In SGML applications, the use of control characters is limited in
order to maximize the chance of successful interchange over
heterogeneous networks and operating systems. In the HTML document
character set only three control characters are allowed: Horizontal
Tab, Carriage Return, and Line Feed (code positions 9, 13, and 10).

The HTML DTD references the Added Latin 1 entity set, to allow
mnemonic representation of selected Latin 1 characters using only the
widely supported ASCII character repertoire. For example:

Kurt Gödel was a famous logician and mathematician.

See 9.7.2, "ISO Latin 1 Character Entity Set" for a table of the
"Added Latin 1" entities, and 13, "The HTML Coded Character Set" for
a table of the code positions of [ISO 8859-1] and the control
characters in the HTML document character set.

7. Hyperlinks

In addition to general purpose elements such as paragraphs and lists,
HTML documents can express hyperlinks. An HTML user agent allows the
user to navigate these hyperlinks.

A hyperlink is a relationship between two anchors, called the head
and the tail of the hyperlink[DEXTER]. Anchors are identified by an
anchor address: an absolute Uniform Resource Identifier (URI),
optionally followed by a '#' and a sequence of characters called a
fragment identifier. For example:

http://www.w3.org/hypertext/WWW/TheProject.html
http://www.w3.org/hypertext/WWW/TheProject.html#z31

In an anchor address, the URI refers to a resource; it may be used in
a variety of information retrieval protocols to obtain an entity that
represents the resource, such as an HTML document. The fragment
identifier, if present, refers to some view on, or portion of the
resource.

Each of the following markup constructs indicates the tail anchor of
a hyperlink or set of hyperlinks:

* <A> elements with HREF present.

* <LINK> elements.

* <IMG> elements.

* <INPUT> elements with the SRC attribute present.

* <ISINDEX> elements.

* <FORM> elements with `METHOD=GET'.

These markup constructs refer to head anchors by a URI, either
absolute or relative, or a fragment identifier, or both.

In the case of a relative URI, the absolute URI in the address of the
head anchor is the result of combining the relative URI with a base
absolute URI as in [RELURL]. The base document is taken from the
document's <BASE> element, if present; else, it is determined as in
[RELURL].

7.1. Accessing Resources

Once the address of the head anchor is determined, the user agent may
obtain a representation of the resource.

For example, if the base URI is `http://host/x/y.html' and the
document contains:

<img src="../icons/abc.gif">

then the user agent uses the URI `http://host/icons/abc.gif' to
access the resource, as in [URL]..

7.2. Activation of Hyperlinks

An HTML user agent allows the user to navigate the content of the
document and request activation of hyperlinks denoted by <A>
elements. HTML user agents should also allow activation of <LINK>
element hyperlinks.

To activate a link, the user agent obtains a representation of the
resource identified in the address of the head anchor. If the
representation is another HTML document, navigation may begin again
with this new document.

7.3. Simultaneous Presentation of Image Resources

An HTML user agent may activate hyperlinks indicated by <IMG> and
<INPUT> elements concurrently with processing the document; that is,
image hyperlinks may be processed without explicit request by the
user. Image resources should be embedded in the presentation at the
point of the tail anchor, that is the <IMG> or <INPUT> element.

<LINK> hyperlinks may also be processed without explicit user
request; for example, style sheet resources may be processed before
or during the processing of the document.

7.4. Fragment Identifiers

Any characters following a `#' character in a hypertext address
constitute a fragment identifier. In particular, an address of the
form `#fragment' refers to an anchor in the same document.

The meaning of fragment identifiers depends on the media type of the
representation of the anchor's resource. For `text/html'
representations, it refers to the <A> element with a NAME attribute
whose value is the same as the fragment identifier. The matching is
case sensitive. The document should have exactly one such element.
The user agent should indicate the anchor element, for example by
scrolling to and/or highlighting the phrase.

For example, if the base URI is `http://host/x/y.html' and the user
activated the link denoted by the following markup:

<p> See: <a href="app1.html#bananas">appendix 1</a>
for more detail on bananas.

Then the user agent accesses the resource identified by
`http://host/x/app1.html'. Assuming the resource is represented using
the `text/html' media type, the user agent must locate the <A>
element whose NAME attribute is `bananas' and begin navigation there.

7.5. Queries and Indexes

The <ISINDEX> element represents a set of hyperlinks. The user can
choose from the set by providing keywords to the user agent. The
user agent computes the head URI by appending `?' and the keywords to
the base URI. The keywords are escaped according to [URL] and joined
by `+'. For example, if a document contains:

<BASE HREF="http://host/index">
<ISINDEX>

and the user provides the keywords `apple' and `berry', then the
user agent must access the resource
`http://host/index?apple+berry'.

<FORM> elements with `METHOD=GET' also represent sets of
hyperlinks. See 8.2.2, "Query Forms: METHOD=GET" for details.

7.6. Image Maps

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="http://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
`http://host/cgi-bin/imagemap?0,0'.

8. Forms

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.

Form processing is a level 2 feature.

8.1. Form Elements

8.1.1. Form: FORM

The <FORM> element contains a sequence of input elements, along
with document structuring elements. The attributes are:

ACTION
specifies the action URI for the form. The action URI of
a form defaults to the base URI of the document (see 7,
"Hyperlinks").

METHOD
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. See 8.2.2, "Query Forms:
METHOD=GET" and 8.2.3, "Forms with Side-Effects:
METHOD=POST".

ENCTYPE
specifies the media type used to encode the name/value
pairs for transport, in case the protocol does not
itself impose a format. See 8.2.1, "The form-urlencoded
Media Type".

8.1.2. Input Field: INPUT

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

The <INPUT> element has a number of attributes. The set of applicable
attributes depends on the value of the TYPE attribute.

8.1.2.1. Text Field: INPUT TYPE=TEXT

The default value of the TYPE attribute is `TEXT', indicating a
single line text entry field. (Use the <TEXTAREA> element for multi-
line text fields.)

Required attributes are:

NAME
name for the form field corresponding to this element.

The optional attributes are:

MAXLENGTH
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.

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

VALUE
The initial value of the field.

For 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>

8.1.2.2. Password Field: INPUT TYPE=PASSWORD

An <INPUT> element with `TYPE=PASSWORD' is a text field as above,
except that the value is obscured as it is entered. (see also: 10,
"Security Considerations").

For example:

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

8.1.2.3. Check Box: INPUT TYPE=CHECKBOX

An <INPUT> element with `TYPE=CHECKBOX' represents a boolean choice.
A set of such elements with the same name represents an n-of-many
choice field. Required attributes are:

NAME
symbolic name for the form field corresponding to this
element or group of elements.

VALUE
The portion of the value of the field contributed by
this element.

Optional attributes are:

CHECKED
indicates that the initial state is on.

For 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>

8.1.2.4. Radio Button: INPUT TYPE=RADIO

An <INPUT> element with `TYPE=RADIO' represents a boolean choice. A
set of such elements with the same name represents a 1-of-many choice
field. The NAME and VALUE attributes are required as for check boxes.
Optional attributes are:

CHECKED
indicates that the initial state is on.
At all times, exactly one of the radio buttons in a set is checked.
If none of the <INPUT> elements of a set of radio buttons specifies
`CHECKED', then the user agent must check the first radio button of
the set initially.

For 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>

8.1.2.5. Image Pixel: INPUT TYPE=IMAGE

An <INPUT> element with `TYPE=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.

The NAME attribute is required as for other input fields. The SRC
attribute is required and the ALIGN is optional as for the <IMG>
element (see 5.10, "Image: IMG").

For example:

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

8.1.2.6. Hidden Field: INPUT TYPE=HIDDEN

An <INPUT> element with `TYPE=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.

For example:

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

8.1.2.7. Submit Button: INPUT TYPE=SUBMIT

An <INPUT> element with `TYPE=SUBMIT' represents an input option,
typically a button, that instructs the user agent to submit the form.
Optional attributes are:

NAME
indicates that this element contributes a form field
whose value is given by the VALUE attribute. If the NAME
attribute is not present, this element does not
contribute a form field.

VALUE
indicates a label for the input (button).

You may submit this request internally:
<input type=submit name=recipient value=internal><br>
or to the external world:
<input type=submit name=recipient value=world>

8.1.2.8. Reset Button: INPUT TYPE=RESET

An <INPUT> element with `TYPE=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).

When you are finished, you may submit this request:
<input type=submit><br>
You may clear the form and start over at any time: <input type=reset>

8.1.3. Selection: SELECT

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

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

NAME
specifies the name of the form field.

SIZE
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.

For 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.

8.1.3.1. Option: OPTION

The Option element can only occur within a Select element. It
represents one choice, and has the following attributes:

SELECTED
Indicates that this option is initially selected.

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

The content of the <OPTION> element is presented to the user to
represent the option. It is used as a returned value if the VALUE
attribute is not present.

8.1.4. Text Area: TEXTAREA

The <TEXTAREA> element represents a multi-line text field.
Attributes are:

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

NAME
Specifies the name of the form field.

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

For 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.

Typically, the ROWS and COLS attributes determine the visible
dimension of the field in characters. The field is typically rendered
in a fixed-width font. HTML user agents should allow text to extend
beyond these limits by scrolling as needed.

8.2. Form Submission

An HTML user agent begins processing a form by presenting the
document with the fields in their initial state. The user is allowed
to modify the fields, constrained by the field type etc. When the
user indicates that the form should be submitted (using a submit
button or image input), the form data set is processed according to
its method, action URI and enctype.

When there is only one single-line text input field in a form, the
user agent should accept Enter in that field as a request to submit
the form.

8.2.1. The form-urlencoded Media Type

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

1. 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'.

2. 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 `http://host/?x=1&y=2' must be
written `<a href="http://host/?x=1&y=2"' or `<a
href="http://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.

8.2.2. Query Forms: METHOD=GET

If the processing of a form is idempotent (i.e. it has no lasting
observable effect on the state of the world), then the form method
should be `GET'. Many database searches have no visible side-effects
and make ideal applications of query forms.

To process a form whose action URL is an HTTP URL and whose method is
`GET', the user agent starts with the action URI and appends a `?'
and the form data set, in `application/x-www-form-urlencoded' format
as above. The user agent then traverses the link to this URI just as
if it were an anchor (see 7.2, "Activation of Hyperlinks").

NOTE - The URL encoding may result in very long URIs, which cause
some historical HTTP server implementations to exhibit defective
behavior. As a result, some HTML forms are written using
`METHOD=POST' even though the form submission has no side-effects.

8.2.3. Forms with Side-Effects: METHOD=POST

If the service associated with the processing of a form has side
effects (for example, modification of a database or subscription to a
service), the method should be `POST'.

To process a form whose action URL is an HTTP URL and whose method is
`POST', the user agent conducts an HTTP POST transaction using the
action URI, and a message body of type `application/x-www-form-
urlencoded' format as above. The user agent should display the
response from the HTTP POST interaction just as it would display the
response from an HTTP GET above.

8.2.4. Example Form Submission: Questionnaire Form

Consider the following document:

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<title>Sample of HTML Form Submission</title>
<H1>Sample Questionnaire</H1>
<P>Please fill out this questionnaire:
<FORM METHOD="POST" ACTION="http://www.w3.org/sample">
<P>Your name: <INPUT NAME="name" size="48">
<P>Male <INPUT NAME="gender" TYPE=RADIO VALUE="male">
<P>Female <INPUT NAME="gender" TYPE=RADIO VALUE="female">
<P>Number in family: <INPUT NAME="family" TYPE=text>
<P>Cities in which you maintain a residence:
<UL>
<LI>Kent <INPUT NAME="city" TYPE=checkbox VALUE="kent">
<LI>Miami <INPUT NAME="city" TYPE=checkbox VALUE="miami">
<LI>Other <TEXTAREA NAME="other" cols=48 rows=4></textarea>
</UL>
Nickname: <INPUT NAME="nickname" SIZE="42">
<P>Thank you for responding to this questionnaire.
<P><INPUT TYPE=SUBMIT> <INPUT TYPE=RESET>
</FORM>

The initial state of the form data set is:

name
""

gender
"male"

family
""

other
""

nickname
""

Note that the radio input has an initial value, while the
checkbox has none.

The user might edit the fields and request that the form be
submitted. At that point, suppose the values are:

name
"John Doe"

gender
"male"

family
"5"

city
"kent"

city
"miami"

other
"abc\ndefk"

nickname
"J&D"

The user agent then conducts an HTTP POST transaction using the URI
`http://www.w3.org/sample'. The message body would be (ignore the
line break):

name=John+Doe&gender=male&family=5&city=kent&city=miami&
other=abc%0D%0Adef&nickname=J%26D

9. HTML Public Text

9.1. HTML DTD

This is the Document Type Definition for the HyperText Markup
Language, level 2.



<!ENTITY % HTML.Version
"-//IETF//DTD HTML 2.0//EN"

-- Typical usage:

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html>
...
</html>
--
>



<!ENTITY % HTML.Recommended "IGNORE"
-- Certain features of the language are necessary for
compatibility with widespread usage, but they may
compromise the structural integrity of a document.
This feature test entity enables a more prescriptive
document type definition that eliminates
those features.
-->

<![ %HTML.Recommended [
<!ENTITY % HTML.Deprecated "IGNORE">

]]>

<!ENTITY % HTML.Deprecated "INCLUDE"
-- Certain features of the language are necessary for
compatibility with earlier versions of the specification,
but they tend to be used and implemented inconsistently,
and their use is deprecated. This feature test entity
enables a document type definition that eliminates
these features.
-->

<!ENTITY % HTML.Highlighting "INCLUDE"
-- Use this feature test entity to validate that a
document uses no highlighting tags, which may be
ignored on minimal implementations.
-->

<!ENTITY % HTML.Forms "INCLUDE"
-- Use this feature test entity to validate that a document
contains no forms, which may not be supported in minimal
implementations
-->



<!ENTITY % Content-Type "CDATA"
-- meaning an internet media type
(aka MIME content type, as per RFC1521)
-->

<!ENTITY % HTTP-Method "GET | POST"
-- as per HTTP specification, in progress
-->



<!ENTITY % heading "H1|H2|H3|H4|H5|H6">

<!ENTITY % list " UL | OL | DIR | MENU " >



<!ENTITY % ISOlat1 PUBLIC
"ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
%ISOlat1;

<!ENTITY amp CDATA "&" -- ampersand -->

<!ENTITY gt CDATA ">" -- greater than -->
<!ENTITY lt CDATA "<" -- less than -->
<!ENTITY quot CDATA """ -- double quote -->





<!ENTITY % SDAFORM "SDAFORM CDATA #FIXED"
-- one to one mapping -->
<!ENTITY % SDARULE "SDARULE CDATA #FIXED"
-- context-sensitive mapping -->
<!ENTITY % SDAPREF "SDAPREF CDATA #FIXED"
-- generated text prefix -->
<!ENTITY % SDASUFF "SDASUFF CDATA #FIXED"
-- generated text suffix -->
<!ENTITY % SDASUSP "SDASUSP NAME #FIXED"
-- suspend transform process -->



<![ %HTML.Highlighting [

<!ENTITY % font " TT | B | I ">

<!ENTITY % phrase "EM | STRONG | CODE | SAMP | KBD | VAR | CITE ">

<!ENTITY % text "#PCDATA | A | IMG | BR | %phrase | %font">

<!ELEMENT (%font;|%phrase) - - (%text)*>
<!ATTLIST ( TT | CODE | SAMP | KBD | VAR )
%SDAFORM; "Lit"

>
<!ATTLIST ( B | STRONG )
%SDAFORM; "B"
>
<!ATTLIST ( I | EM | CITE )
%SDAFORM; "It"
>













<!ENTITY % pre.content "#PCDATA | A | HR | BR | %font | %phrase">

]]>

<!ENTITY % text "#PCDATA | A | IMG | BR">

<!ELEMENT BR - O EMPTY>
<!ATTLIST BR
%SDAPREF; "&#RE;"
>





<!ENTITY % linkType "NAMES">

<!ENTITY % linkExtraAttributes
"REL %linkType #IMPLIED
REV %linkType #IMPLIED
URN CDATA #IMPLIED
TITLE CDATA #IMPLIED
METHODS NAMES #IMPLIED
">

<![ %HTML.Recommended [
<!ENTITY % A.content "(%text)*"

-- <H1><a name="xxx">Heading</a></H1>
is preferred to
<a name="xxx"><H1>Heading</H1></a>
-->
]]>

<!ENTITY % A.content "(%heading|%text)*">

<!ELEMENT A - - %A.content -(A)>
<!ATTLIST A
HREF CDATA #IMPLIED
NAME CDATA #IMPLIED
%linkExtraAttributes;
%SDAPREF; "<Anchor: #AttList>"
>











<!ELEMENT IMG - O EMPTY>
<!ATTLIST IMG
SRC CDATA #REQUIRED
ALT CDATA #IMPLIED
ALIGN (top|middle|bottom) #IMPLIED
ISMAP (ISMAP) #IMPLIED
%SDAPREF; "<Fig><?SDATrans Img: #AttList>#AttVal(Alt)</Fig>"
>









<!ELEMENT P - O (%text)*>
<!ATTLIST P
%SDAFORM; "Para"
>





<!ELEMENT HR - O EMPTY>
<!ATTLIST HR
%SDAPREF; "&#RE;&#RE;"
>



<!ELEMENT ( %heading ) - - (%text;)*>
<!ATTLIST H1
%SDAFORM; "H1"
>
<!ATTLIST H2
%SDAFORM; "H2"
>
<!ATTLIST H3
%SDAFORM; "H3"
>
<!ATTLIST H4
%SDAFORM; "H4"
>
<!ATTLIST H5
%SDAFORM; "H5"
>
<!ATTLIST H6
%SDAFORM; "H6"
>










<![ %HTML.Forms [
<!ENTITY % block.forms "BLOCKQUOTE | FORM | ISINDEX">
]]>

<!ENTITY % block.forms "BLOCKQUOTE">

<![ %HTML.Deprecated [
<!ENTITY % preformatted "PRE | XMP | LISTING">
]]>

<!ENTITY % preformatted "PRE">

<!ENTITY % block "P | %list | DL
| %preformatted
| %block.forms">

<!ENTITY % flow "(%text|%block)*">

<!ENTITY % pre.content "#PCDATA | A | HR | BR">
<!ELEMENT PRE - - (%pre.content)*>
<!ATTLIST PRE
WIDTH NUMBER #implied
%SDAFORM; "Lit"
>




<![ %HTML.Deprecated [

<!ENTITY % literal "CDATA"
-- historical, non-conforming parsing mode where
the only markup signal is the end tag
in full
-->

<!ELEMENT (XMP|LISTING) - - %literal>
<!ATTLIST XMP
%SDAFORM; "Lit"
%SDAPREF; "Example:&#RE;"
>
<!ATTLIST LISTING
%SDAFORM; "Lit"
%SDAPREF; "Listing:&#RE;"
>




<!ELEMENT PLAINTEXT - O %literal>


<!ATTLIST PLAINTEXT
%SDAFORM; "Lit"

>
]]>



<!ELEMENT DL - - (DT | DD)+>
<!ATTLIST DL
COMPACT (COMPACT) #IMPLIED
%SDAFORM; "List"
%SDAPREF; "Definition List:"
>

<!ELEMENT DT - O (%text)*>
<!ATTLIST DT
%SDAFORM; "Term"
>

<!ELEMENT DD - O %flow>
<!ATTLIST DD
%SDAFORM; "LItem"
>






<!ELEMENT (OL|UL) - - (LI)+>
<!ATTLIST OL
COMPACT (COMPACT) #IMPLIED
%SDAFORM; "List"
>
<!ATTLIST UL
COMPACT (COMPACT) #IMPLIED
%SDAFORM; "List"
>





<!ELEMENT (DIR|MENU) - - (LI)+ -(%block)>
<!ATTLIST DIR
COMPACT (COMPACT) #IMPLIED
%SDAFORM; "List"
%SDAPREF; "<LHead>Directory</LHead>"
>

<!ATTLIST MENU
COMPACT (COMPACT) #IMPLIED
%SDAFORM; "List"
%SDAPREF; "<LHead>Menu</LHead>"
>






<!ELEMENT LI - O %flow>
<!ATTLIST LI
%SDAFORM; "LItem"
>





<![ %HTML.Recommended [
<!ENTITY % body.content "(%heading|%block|HR|ADDRESS|IMG)*"
-- <h1>Heading</h1>
<p>Text ...
is preferred to
<h1>Heading</h1>
Text ...
-->
]]>

<!ENTITY % body.content "(%heading | %text | %block |
HR | ADDRESS)*">

<!ELEMENT BODY O O %body.content>



<!ELEMENT BLOCKQUOTE - - %body.content>
<!ATTLIST BLOCKQUOTE
%SDAFORM; "BQ"
>



<!ELEMENT ADDRESS - - (%text|P)*>
<!ATTLIST ADDRESS
%SDAFORM; "Lit"
%SDAPREF; "Address:&#RE;"

>





<![ %HTML.Forms [

<!ELEMENT FORM - - %body.content -(FORM) +(INPUT|SELECT|TEXTAREA)>
<!ATTLIST FORM
ACTION CDATA #IMPLIED
METHOD (%HTTP-Method) GET
ENCTYPE %Content-Type; "application/x-www-form-urlencoded"
%SDAPREF; "<Para>Form:</Para>"
%SDASUFF; "<Para>Form End.</Para>"
>






<!ENTITY % InputType "(TEXT | PASSWORD | CHECKBOX |
RADIO | SUBMIT | RESET |
IMAGE | HIDDEN )">
<!ELEMENT INPUT - O EMPTY>
<!ATTLIST INPUT
TYPE %InputType TEXT
NAME CDATA #IMPLIED
VALUE CDATA #IMPLIED
SRC CDATA #IMPLIED
CHECKED (CHECKED) #IMPLIED
SIZE CDATA #IMPLIED
MAXLENGTH NUMBER #IMPLIED
ALIGN (top|middle|bottom) #IMPLIED
%SDAPREF; "Input: "
>

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RFC1866 - Hypertext Markup Language - 2.0(2)