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Distribution of this document is unlimited.The document is a draft form of a standard for interchange of information on the network which is proposed to be registered as a MIME (RFC1341) content type. Please send comments to email@example.com or the discussion list
This is version 1.2 of this draft. This document is available in hypertext on the World-Wide Web as
HyperText Markup Language (HTML) can be used to represent
Hypertext news, mail, online documentation, and collaborative hypermedia;
Menus of options;
Database query results;
Simple structured documents with inlined graphics.
Hypertext views of existing bodies of information
The World Wide Web (W3) initiative links related information
throughout the globe. HTML provides one simple format for providing
linked information, and all W3 compatible programs are required
to be capable of handling HTML. W3 uses an Internet
HTML is proposed as a MIME content type.
HTML refers to the URL specification of RFCxxxx.
Implementations of HTML parsers and generators can be found in the various W3 servers and browsers, in the public domain W3 code, and may also be built using various public domain SGML parsers such as [SGMLS]. HTML is an SGML document type with fairly generic semantics appropriate for representing information from a wide range of applications. It is more generic than many specific SGML applications, but is still completely device-independent.
This document contains the following parts:
table of contents
Sections marked "Note:" are not mandatory parts of the specification but for guidance only.
STATUS OF FEATURES
The definition of the HTML content subtype is
The base character set (the SGML BASESET) for HTML is ISO Latin-1. This is the set referred to by any numeric character references . The actual character set used in the representation of an HTML document may be ISO Latin 1, or its 7-bit subset which is ASCII. There is no obligation for an HTML document to contain any characters above decimal 127. It is possible that a transport medium such as electronic mail imposes constraints on the number of bits in a representation of a document, though the HTTP access protocol used by W3 always allows 8 bit transfer.
When an HTML document is encoded using 7-bit characters, then the mechanisms of character references and entity references may be used to encode characters in the upper half of the ISO Latin-1 set. In this way, documents may be prepared which are suitable for mailing through 7-bit limited systems.
The HyperText Markup Language is defined in terms of the ISO Standard Generalized Markup Language . SGML is a system for defining structured document types and markup languages to represent instances of those document types.
Every SGML document has three parts:
An SGML declaration, which binds SGML processing quantities
and syntax token names to specific values. For example, the SGML
declaration in the HTML DTD specifies that the string that opens
A prologue including one or more document type declarations, which specifiy the element types, element relationships and attributes, and references that can be represented by markup. The HTML DTD specifies, for example, that the HEAD element contains at most one TITLE element.
Die Autoren setzen explizit voraus, dass die DTD Teil der document type declaration(s) ist, wie es Goldfarb auf Seite 403 des SGML Handbook klarstellt. Es konnte damals noch nicht klar sein, dass HTML eine Sonderstellung unter den SGML Dokumententypen haben wird, bei der dies keine Rolle spielt. Conolly und Berners-Lee vertreten in dieser Frage zwei Extreme. Conolly will HTML zu einer »reinen« SGML DTD machen. Berners-Lee möchte »nur« seinen Traum des weltumspannenden Netzes von »arrows and nodes« in die Tat umsetzen und sich von den schwerfällig scheinenden Zwängen von SGML nicht behindern lassen. In wenigen Jahren wird HTML in der Version 4.01 die richtige Mitte zwischen diesen beiden Extremen finden.
An instance, which contains the data and markup of the document.
We use the term HTML to mean both the document type and the markup
All HTML documents share the same SGML declaration an
Conversely, to implement an HTML parser, one need only implement those parts of an SGML parser that are needed to parse an instance after parsing the HTML DTD.
An HTML instance is like a text file, except that some of the characters are interpreted as markup. The markup gives structure to the document.
The instance represents a hierarchy of elements. Each element has a name , some attributes, and some content. Most elements are represented in the document as a start tag, which gives the name and attributes, followed by the content, followed by the end tag. For example:
<TITLE> A sample HTML instance </TITLE>
<H1> An Example of Structure </H1>
Here's a typical paragraph.
Item one has an
<LI> Here's item two.
Some elements (e.g. P, LI) are empty. They have no content. They show up as just a start tag.
<P> und <LI> als "empty" elements
For the rest of the elements, the content is a sequence of data
characters and nested elements. Note that the HTML DTD in fact
severely limits the amount of nesting which is allowed: most things
Anchors and character highlighting may be put inside other constructs.
Every element starts with a tag, and every non-empty element ends with a tag. Start tags are delimited by < and >, and end tags are delimited by </ and >.
The element name immediately follows the tag open delimiter. Names consist of a letter followed by up to 33 letters, digits, periods, or hyphens. Names are not case sensitive.
In a start tag, whitespace and attributes are allowed between the element name and the closing delimiter. An attribute consists of a name, an equal sign, and a value. Whitespace is allowed around the equal sign.
The value is specified in a string surrounded by single quotes or a string surrounded by double quotes. (See: other tolerated forms @@)
The string is parsed like RCDATA (see below ) to determine the attribute value. This allows, for example, quote characters in attribute values to be represented by character references.
The length of an attribute value (after parsing) is limited to 1024 characters.
The name of a tag refers to an element type declaration in the HTML DTD. An element type declaration associates an element name with
A list of attributes and their types and statuses
A content type (one of EMPTY, CDATA, RCDATA, ELEMENT, or MIXED) which determines the syntax of the element's content
A content model, which specifies the pattern of nested elements and data
Empty elements have the keyword EMPTY in their declaration. For example:
<!ELEMENT NEXTID - O EMPTY>
<!ATTLIST NEXTID N NUMBER #REQUIRED>
This means that the following:
is legal, but these others are not:
The keyword CDATA indicates that the content of an element is character data. Character data is all the text up to the next end tag open delimiter-in-context. For example:
<!ELEMENT XMP - - CDATA>
specifies that the following text is a legal XMP element:
The string </ is only recognized as the opening delimiter of an end tag when it is "in context," that is, when it is followed by a letter. However, as soon as the end tag open delimiter is recognized, it terminates the CDATA content. The following is an error:
<xmp>There is no way to represent </end> tags in CDATA </xmp>
Elements with RCDATA content behave much like those with CDATA, except for character references and entity references. Elements declared like:
<!ELEMENT TITLE - - RCDATA>
can have any sequence of characters in their content.
To represent a character that would otherwise be recognized as markup, use a character reference. The string &# signals a character reference when it is followed by a letter or a digit. The delimiter is followed by the decimal character number and a semicolon. For example:
<title>You can even represent </end> tags
in RCDATA </title>
The HTML DTD declares entities for the less than, greater than, and ampersand characters and each of the ISO Latin 1 characters so that you can reference them by name rather than by number.
The string & signals an entity reference when it is followed by a letter or a digit. The delimiter is followed by the entity name and a semicolon. For example:
Kurt Gödel was a famous logician and mathematician.
Note: To be sure that a string of characters has no markup, HTML writers should represent all occurrences of <, >, and & by character or entity references.
Some elements have, instead of a keyword that states the type of content, a content model, which tells what patterns of data and nested elements are allowed. If the content model of an element does not include the symbol #PCDATA, the content is element content.
Whitespace in element content is considered markup and ignored. Any characters that are not markup, that is, data characters, are illegal.
<!ELEMENT HEAD - - (TITLE? & ISINDEX? & NEXTID? & LINK*)>
declares an element that may be used as follows:
<head> <isindex> <title>Head Example</title> </head>
But the following are illegal:
<head> no data allowed! </head>
<head><isindex><title>Two isindex tags</title><isindex></head>
If the content model includes the symbol #PCDATA, the content of the element is parsed as mixed content. For example:
<!ELEMENT PRE - - (#PCDATA | A | B | I | U | P)+>
<!ATTLIST PRE WIDTH NUMBER #implied
This says that the PRE element contains one or more A, B, I, U, or P elements or data characters. Here's an example of a PRE element:
<pre> <b>NAME</b> cat -- concatenate <a href="terms.html#file">files</a> <b>EXAMPLE</b> cat <xyz </pre>
The content of the above PRE element is:
A B element
The string "cat -- concatenate"
An A element
The string "∖n"
Another B element
The string "∖ncat <xyz"
To include comments in an HTML document that will be ignored by the parser, surround them with <!-- and -->. After the comment delimiter, all text up to the next occurrence of -- is ignored. Hence comments cannot be nested. Whitespace is allowed between the closing -- and >. (But not between the opening <! and --.)
<TITLE>HTML Guide: Recommended Usage</TITLE>
<!-- $Id: HTML.txt,v 1.2 1994/04/12 23:13:42 connolly Exp $ -->
There are a few other SGML markup constructs that are deprecated or illegal.
A line break character is considered markup (and ignored) if it is the first or last piece of content in an element. This allows you to write either
<PRE>some example text</pre>
some example text
and these will be processed identically.
Also, a line that's not empty but contains no content will be ignored altogether. For example, the element
<!-- this line is ignored, including the linebreak character --> first line
third line<!-- the following linebreak is content: -->
fourth line<!-- this one's ignored because it's the last piece of cont ent: -->
contains only the strings
Space characters must be rendered as horizontal white space. In HTML, multiple spaces should be rendered as proportionally larger spaces.
The rendering of a horizontal tab (HT) character is not defined, and HT should therefore not be used, except within a PRE (or obsolete XMP, LISTING or PLAINTEXT) element.
Neither spaces nor tabs should be used to make SGML source layout more attractive or easier to read.
The following delimiters may signal markup, depending on context.
|Marked section close (an error)|
This is a list of elements used in the HTML language. Documents should (but need not absolutely) contain an initial HEAD element followed by a BODY element.
Old style documents may contain a just the contents of the normal HEAD and BODY elements, in any order. This is deprecated but must be supported by parsers.
See also: Status of elements
Properties of the whole document
Properties of the whole document are defined by the following elements. They should appear within the HEAD element. Their order is not significant.
All attributes are optional, although one of NAME and HREF is necessary for the anchor to be useful. See also: LINK.
EXAMPLE OF USE: See <A HREF="http://info.cern.ch/">CERN</A>'s information for more details.
A <A NAME=serious>serious</A> crime is one which is associated with imprisonment. ... The Organization may refuse employment to anyone convicted of a <a href="#serious">serious</A> crime.
NOTE : UNIVERSAL RESOURCE NUMBERS
URNs are provided to allow a document to be recognized if duplicate copies are found. This should save a client implementation from picking up a copy of something it already has.
The format of URNs is under discussion (1993) by various working groups of the Internet Engineering Task Force.
NOTE: TITLE ATTRIBUTE OF LINKS
The link may carry a TITLE attribute which should if present give the title of the document whose address is given by the HREF attribute.
This is useful for at least two reasons
The browser software may chose to display the title of the document as a preliminary to retrieving it, for example as a margin note or on a small box while the mouse is over the anchor, or during document fetch.
Some documents -- mainly those which are not marked up text,
such as graphics, plain text and also Gopher menus, do not come
with a title themselves, and so putting a title in the link is the
only way to give them a title. This is how Gopher works. Obviously
it leads to duplication of data, and so it is
NOTE: METHODS ATTRIBUTE OF LINKS
The METHODS attributes of anchors and links are used to provide information about the functions which the user may perform on an object. These are more accurately given by the HTTP protocol when it is used, but it may, for similar reasons as for the TITLE attribute, be useful to include the information in advance in the link.
For example, The browser may chose a different rendering as a function of the methods allowed (for example something which is searchable may get a different icon)
This element allows the URL of the document itself to be recorded in situations in which the document may be read out of context. URLs within the document may be in a "partial" form relative to this base address.
Where the base address is not specified, the reader will use the URL it used to access the document to resolve any relative URLs.
The one attribute is:
HREF the URL
The BLOCKQUOTE element allows text quoted from another source to be rendered specially.
TYPICAL RENDERING A typical rendering might be a slight extra left and right indent, and/or italic font. BLOCKQUOTE causes a paragraph break, and typically a line or so of white space will be allowed between it and any text before or after it.
Single-font rendition may for example put a vertical line of ">" characters down the left margin to indicate quotation in the Internet mail style.
I think it ends
<BLOCKQUOTE>Soft you now, the fair Ophelia. Nymph, in thy orisons, be all my sins remembered.
but I am not sure.
Six levels of heading are supported. (Note that a hypertext node within a hypertext work tends to need less levels of heading than a work whose only structure is given by the nesting of headings.)
A heading element implies all the font changes, paragraph breaks before and after, and white space (for example) necessary to render the heading. Further character emphasis or paragraph marks are not required in HTML.
H1 is the highest level of heading, and is recommended for the start of a hypertext node.It is suggested that the the text of the first heading be suitable for a reader who is already browsing in related information, in contrast to the title tag which should identify the node in a wider context.
The heading elements are
<H1>, <H2>, <H3>, <H4>, <H5>, <H6>
It is not normal practice to jump from one header to a header
level more than one below, for example for follow an H1 with an
H3. Although this is legal, it is discouraged, as it may produce
strange results for example when generating other representations
from the HTML.
<H1>This is a heading</H1>
Here is some text
<H2>Second level heading</H2>
Here is some more text.
Parsers should not require any specific order to heading elements, even if the heading level increases by more than one between successive headings.
H1 Bold very large font, centered. One or two lines clear space between this and anything following. If printed on paper, start new page.
H2 Bold, large font,, flush left against left margin, no indent. One or two clear lines above and below.
H3 Italic, large font, slightly indented from the left margin. One or two clear lines above and below.
H4 Bold, normal font, indented more than H3. One clear line above and below.
H5 Italic, normal font, indented as H4. One clear line above.
H6 Bold, indented same as normal text, more than H5. One clear line above.
These typical values are just an indication, and it is up to the designer of the presentation software to define the styles. The reader may have options to customize these. When writing documents, you should assume that whatever is done it is designed to have the same sort of effect as the styles above.
The rendering software is responsible for generating suitable vertical white space between elements, so it is NOT normal or required to follow a heading element with a paragraph mark.
IMG: Embedded Images
The IMG element allows another document to be inserted inline.
The document is normally an icon or small graphic, etc. This element
Browsers which are not able to display inline images ignore IMG elements. Authors should note that some browsers will be able to display (or print) linked graphics but not inline graphics. If the graphic is essential, it may be wiser to make a link to it rather than to put it inline. If the graphic is essentially decorative, then IMG is appropriate.
The IMG element is empty: it has no closing tag. It has two attributes:
The value of this attribute is the URL of the document to be embedded. Its syntax is the same as that of the HREF attribute of the A tag. SRC is mandatory.
Take values TOP or MIDDLE or BOTTOM, defining whether the tops or middles of bottoms of the graphics and text should be aligned vertically.
Optional alternative text as an alternative to the graphics for display in text-only environments. Note that IMG elements are allowed within anchors.
Warning: < IMG SRC ="triangle.gif" ALT="Warning:"> This must be done by a qualified technician.
< A HREF="Go">< IMG SRC ="Button"> Press to start</A>
This element informs the reader that the document is an index document. As well as reading it, the reader may use a keyword search.
The node may be queried with a keyword search by suffixing the node address with a question mark, followed by a list of keywords separated by plus signs. See the network address format .
Note that this tag is normally generated automatically by a server.
If it is added by hand to an HTML document, then the client will
assume that the server can handle a search on the document.
Obviously the server must have this capability for it to work: simply adding <ISINDEX> in the document is not enough to make searches happen if the server does not have a search engine!
EXAMPLE OF USE:
The LINK element occurs within the HEAD element of an HTML document. It is used to indicate a relationship between the document and some other object. A document may have any number of LINK elements.
The LINK element is empty, but takes the same attributes as the anchor element.
Typical uses are to indicate authorship, related indexes and glossaries, older or more recent versions, etc. Links can indicate a static tree structure in which the document was authored by pointing to a "parent" and "next" and "previous" document, for example.
Servers may also allow links to be added by those who do not have the right to alter the body of a document.
Forms of list in HTML
A glossary (or definition list) is a list of paragraphs each of which has a short title alongside it. Apart from glossaries, this element is useful for presenting a set of named elements to the reader. The elements within a glossary follow are
DT The "term", typically placed in a wide left indent
DD The "definition", which may wrap onto many lines These elements must appear in pairs. Single occurrences of DT without a following DD are illegal. The one attribute which DL can take is
suggests that a compact rendering be used, because the enclosed
elements are individually small, or the whole glossary is rather
large, or both.
The definition list DT, DD pairs are arranged vertically.For each pair, the DT element is on the left, in a column of about a third of the display area, and the DD element is in the right hand two thirds of the display area. The DT term is normally small enough to fit on one line within the left-hand column. If it is longer, it will either extend across the page, in which case the DD section is moved down to separate them, or it is wrapped onto successive lines of the left hand column.
White space is typically left between successive DT,DD pairs unless the COMPACT attribute is given. The COMPACT attribute is appropriate for lists which are long and/or have DT,DD pairs which each take only a line or two. It is of course possible for the rendering software to discover these cases itself and make its own decisions, and this is to be encouraged.
The COMPACT attribute may also reduce the width of the left-hand (DT) column.
Examples of use
<DT>Term the first<DD>definition paragraph is reasonably long but is still displayed clearly
<DT>Term2 follows<DD>Definition of term2
<DT>Term2<DD>Definition of term2
A list is a sequence of paragraphs, each of which may be preceded by a special mark or sequence number. The syntax is:
<LI> list element
<LI> another list element ...
The opening list tag may be any of UL, OL, MENU or DIR. It must be immediately followed by the first list element.
The representation of the list is not defined here, but a bulleted list for unordered lists, and a sequence of numbered paragraphs for an ordered list would be quite appropriate. Other possibilities for interactive display include embedded scrollable browse panels.
List elements with typical rendering are:
Example of use
<LI> When you get to the station, leave by the southern exit, on platform one.
<LI>Turn left to face toward the mountain
<LI>Walk for a mile or so until you reach the "Asquith Arms" then
<LI>Wait and see...
< MENU >
<LI>The oranges should be pressed fresh
<LI>The nuts may come from a packet
<LI>The gin must be good quality
< DIR >
This tag takes a single attribute which is the number of the next document-wide numeric identifier to be allocated of the form z123.
When modifying a document, old anchor ids should not be reused, as there may be references stored elsewhere which point to them. This is read and generated by hypertext editors. Human writers of HTML usually use mnemonic alphabetical identifiers. Browser software may ignore this tag.
EXAMPLE OF USE:
P: Paragraph mark
The empty P element indicates a paragraph break. The exact rendering of this (indentation, leading, etc) is not defined here, and may be a function of other tags, style sheets etc.
<P> is used between two pieces of text which otherwise would be flowed together.
You do NOT need to use <P> to put white space around heading, list, address or blockquote elements which imply a paragraph break. It is the responsibility of the rendering software to generate that white space. A paragraph mark which is preceded or followed by such elements which imply a paragraph break is has undefined effect and should be avoided.
Typically, <P> will generate a small vertical space (of a line or half a line) between the paragraphs. This is not the case (typically) within ADDRESS or (ever) within PRE elements.With some implementations, in normal text, <P> may generate a small extra left indent on the first line.
EXAMPLES OF USE
<h1>What to do</h1>
This is a one paragraph.< p >
This is a second. < P >
This is a third.
<h1><P>What not to do</h1>
<p>I found that on my XYZ browser it looked prettier to me if I put some paragraph marks
<ul><p><li>Around lists, and
None of the paragraph marks in this example should be there.
<ich date="16.01.2018">Dass Conolly das P Element als EMPTY zulässt, zeugt entweder von der Hartnäckigkeit Berners-Lee's, oder von mangelndem Verständnis von SGML. Ich glaube eher ersteres, denn dass er den BODY als mixed content und nicht als element content haben will, zeugt von einem klaren Verständnis des HTML BODY. So unscheinbar er ist: Der Paragraph ist die "Arbeitsbiene" jedes SGML Dokuments. Aus dem Paragraphen setzt sich das ganze SGML Dokument zusammen. Er verdient daher die ganze Aufmerksamkeit des DTD Autors. Einen Paragraphen als ein Element ohne content zu deklarieren, ist absurd, weil dies ein inhaltsloses Dokument zur Folge hat.
Das ist Besserwisserei, weg damit bzw. als deine Besserwisserei stehenlassen: Das Dokument ist ein DRAFT, und in einem DRAFT ist ALLES erlaubt! Außerdem lenkst du damit vom eigentlich wichtigen BODY ab, in dem tatsächlich ALLES erlaubt ist. Und das ist dort ein Fortschritt über das traditionelle SGML hinaus. Außerdem: In keiner recommendation des w3c ist der p ein leeres element, nur in diesem DRAFT. Wenn du Berners-Lee anpinkeln willst, muss das an wichtigeren Stellen geschehen!</ich>
PRE: Preformatted text
Preformatted elements in HTML are displayed with text in a fixed width font, and so are suitable for text which has been formatted for a teletype by some existing formatting system.
The optional attribute is:
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.
Within a PRE element,
Line boundaries within the text are rendered as a move to the beginning of the next line, except for one immediately following or immediately preceding a tag.
The <p> tag should not be used. If found, it should be rendered as a move to the beginning of the next line.
Anchor elements and character highlighting elements may be used.
Elements which define paragraph formatting (Headings, Address, etc) must not be used.
The ASCII Horizontal Tab (HT) character 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. Its use is not recommended however.
Example of use
This is an example line
Note: Highlighting Within a preformatted element, the constraint that the rendering must be on a fixed horizontal character pitch may limit or prevent the ability of the renderer to render highlighting elements specially.
Note: Margins The above references to the "beginning of a new line" must not be taken as implying that the renderer is forbidden from using a (constant) left indent for rendering preformatted text. The left indent may of course be constrained by the width required.
The title of a document is specified by the TITLE element. The TITLE element should occur in the HEAD of the document.
There may only be one title in any document. It should identify the content of the document in a fairly wide context.
The title is not part of the text of the document, but is a property of the whole document. It may not contain anchors, paragraph marks, or highlighting. The title may be used to identify the node in a history list, to label the window displaying the node, etc. It is not normally displayed in the text of a document itself. Contrast titles with headings . The title should ideally be less than 64 characters in length. That is, many applications will display document titles in window titles, menus, etc where there is only limited room. Whilst there is no limit on the length of a title (as it may be automatically generated from other data), information providers are warned that it may be truncated if long.
Examples of use
Appropriate titles might be
<TITLE>Rivest and Neuman. 1989(b)</TITLE>
<TITLE>A Recipe for Maple Syrup Flap-Jack</TITLE>
<TITLE>Introduction -- AFS user's Guide</TITLE>
Examples of inappropriate titles are those which are only meaningful within context,
or too long,
<TITLE>Remarks on the Quantum-Gravity effects of "Bean Pole" diversification in Mononucleosis patients in Developing Countries under Economic Conditions Prevalent during the Second half of the Twentieth Century, and Related Papers: a Summary</TITLE>
These elements allow sections of text to be formatted in a particular way, to provide emphasis, etc. The tags do NOT cause a paragraph break, and may be used on sections of text within paragraphs.
Where not supported by implementations, like all tags, these tags should be ignored but the content rendered.
All these tags have related closing tags, as in
This is <EM>emphasized</EM> text.
Some of these styles are more explicit than others about how they should be physically represented. The logical styles should be used wherever possible, unless for example it is necessary to refer to the formatting in the text. (Eg, "The italic parts are mandatory".)
Note: Browsers unable to display a specified style may render it in some alternative, or the default, style, with some loss of quality for the reader. Some implementations may ignore these tags altogether, so information providers should attempt not to rely on them as essential to the information content.
These element names are derived from TeXInfo macro names.
EXAMPLES OF USE
This text contains an <em>emphasized</em> word. <strong>Don't assume</strong> that it will be italic! It was made using the <CODE>EM</CODE> element. A citation is typically italic and has no formal necessary structure: <cite>Moby Dick</cite> is a book title.
The following elements of HTML are obsolete.
It is recommended that client implementors implement the obsolete forms for compatibility with old servers.
Status: Obsolete .
The empty PLAINTEXT tag terminates the HTML entity. What follows is not SGML. In stead, there's an old HTTP convention that what follows is an ASCII (MIME "text/plain") body.
An example if its use is:
0001 This is line one of a ling listing
0002 file from <firstname.lastname@example.org> which
This tag allows the rest of a file to be read efficiently without parsing. Its presence is an optimization. There is no closing tag. The rest of the data is not in SGML.
XMP and LISTING: Example sections
Status: Obsolete . This are in use and should be recognized by browsers. New servers should use <PRE> instead.
These styles allow text of fixed-width characters to be embedded absolutely as is into the document. The syntax is:
The text between these tags is to be portrayed in a fixed width font, so that any formatting done by character spacing on successive lines will be maintained. Between the opening and closing tags:
The text may contain any ISO Latin printable characters, but not the end tag opener. (See Historical note )
Line boundaries are significant, except any occurring immediately after the opening tag or before the closing tag. and are to be rendered as a move to the start of a new line.
The ASCII Horizontal Tab (HT) character 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. Its use is not recommended however.
The LISTING element is portrayed so that at least 132 characters will fit on a line. The XMP elementis portrayed in a font so that at least 80 characters will fit on a line but is otherwise identical to LISTING.
Highlighted Phrase HP1 etc
Status: Obsolete .
These tags like all others should be ignored if not implemented. Replaced will more meaningful elements -- see character highlighting .
Examples of use:
<HP1>...</HP1><HP2>... </HP2> etc.
A comment element used for bracketing off unneed text and comment has been introduced in some browsers but will be replaced by the SGML command feature in new implementations.
HISTORICAL NOTE: XMP AND LISTING
The XMP and LISTING elements used historically to have non SGML conforming specifications, in that the text could contain any ISO Latin printable characters, including the tag opener, so long as it does not contain the closing tag in full.
This form is not supported by SGML and so is not the specified HTML interpretation. Providers should be warned that implementations may vary on how they interpret end tags apparently within these elements
The following entity names are used in HTML, always prefixed by ampersand (&) and followed by a semicolon as shown. They represent particular graphic characters which have special meanings in places in the markup, or may not be part of the character set available to the writer.
< The less than sign <
> The "greater than" sign >
& The ampersand sign & itself.
" The double quote sign " Also allowed are references to any of the ISO Latin-1 alphabet, using the entity names in the following table.
ISO Latin 1 character entities
This list is derived from "ISO 8879:1986//ENTITIES Added Latin 1//EN".
|Æ||capital AE diphthong (ligature)|
|Á||capital A, acute accent|
|Â||capital A, circumflex accent|
|À||capital A, grave accent|
|Å||capital A, ring|
|Ã||capital A, tilde|
|Ä||capital A, dieresis or umlaut mark|
|Ç||capital C, cedilla|
|Ð||capital Eth, Icelandic|
|É||capital E, acute accent|
|Ê||capital E, circumflex accent|
|È||capital E, grave accent|
|Ë||capital E, dieresis or umlaut mark|
|Í||capital I, acute accent|
|Î||capital I, circumflex accent|
|Ì||capital I, grave accent|
|Ï||capital I, dieresis or umlaut mark|
|Ñ||capital N, tilde|
|Ó||capital O, acute accent|
|Ô||capital O, circumflex accent|
|Ò||capital O, grave accent|
|Ø||capital O, slash|
|Õ||capital O, tilde|
|Ö||capital O, dieresis or umlaut mark|
|Þ||capital THORN, Icelandic|
|Ú||capital U, acute accent|
|Û||capital U, circumflex accent|
|Ù||capital U, grave accent|
|Ü||capital U, dieresis or umlaut mark|
|Ý||capital Y, acute accent|
|á||small a, acute accent|
|â||small a, circumflex accent|
|æ||small ae diphthong (ligature)|
|à||small a, grave accent|
|å||small a, ring|
|ã||small a, tilde|
|ä||small a, dieresis or umlaut mark|
|ç||small c, cedilla|
|é||small e, acute accent|
|ê||small e, circumflex accent|
|è||small e, grave accent|
|ð||small eth, Icelandic|
|ë||small e, dieresis or umlaut mark|
|í||small i, acute accent|
|î||small i, circumflex accent|
|ì||small i, grave accent|
|ï||small i, dieresis or umlaut mark|
|ñ||small n, tilde|
|ó||small o, acute accent|
|ô||small o, circumflex accent|
|ò||small o, grave accent|
|ø||small o, slash|
|õ||small o, tilde|
|ö||small o, dieresis or umlaut mark|
|ß||small sharp s, German (sz ligature)|
|þ||small thorn, Icelandic|
|ú||small u, acute accent|
|û||small u, circumflex accent|
|ù||small u, grave accent|
|ü||small u, dieresis or umlaut mark|
|ý||small y, acute accent|
|ÿ||small y, dieresis or umlaut mark|
The HTML DTD follows . Its relationship to the content of an SGML document is explained in the section "HTML and SGML" .
<!SGML "ISO 8879:1986"
-- Document Type Definition for the HyperText Markup Language as used by the World Wide Web application (HTML DTD).
NOTE: This is a definition of HTML with respect to SGML, and assumes an understanding of SGML terms. --
"ISO 646:1983//CHARSET International Reference Version (IRV)//ESC 2/5 4/0"
9 2 9
11 2 UNUSED
13 1 13
14 18 UNUSED
32 95 32
127 1 UNUSED
"ISO Registration Number 100//CHARSET ECMA-94 Right Part of Latin Alphabet Nr. 1//ESC 2/13 4 /1"
128 32 UNUSED
160 95 32
255 1 UNUSED
0 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19
20 21 22 23 24 25 26 27 28 29
30 31 127 255
"ISO 646:1983//CHARSET International Reference Version (IRV)//ESC 2/5 4/0"
DESCSET 0 128 0
TAB SEPCHAR 9
APPINFO NONE >
Status: This list is not part of the standard. It is intended to illustrate the use of link relationships and to provide a framework for further development.
Additions to this list will be controlled by the HTML registration authority . Experimental values may be used on the condition that they begin with "X-".
These values of the REL attribute of hypertext links have a significance defined here, and may be treated in special ways by HTML applications.
These relationships relate whole documents (objects), rather than particular anchors within them. If the relationship value is used with a link between anchors rather than whole documents, the semantics are considered to apply to the documents.
In the explanations which follows, A is the source document of the link and B is the destination document specified by the HREF attribute.
A relationship marked "Acyclic" has the property that no sequence of links with that relationship may be followed from any document back to itself. These types of links may therefore be used to define trees.
Relationships between documents
These relationships are between the documents themselves rather than the subjects of the documents.
USEINDEX B is a related index for a search by a user reading this document who asks for an index search function.
A document may have any number of index links, causing several indexes top be searched in a client-defined manner.
B must support SEARCH operations under its access protocol.
USEGLOSSARY B is an index which should be used to resolve glossary queries in the document. (Typically, a double-click on a word which is not within an anchor).
A document may have any number of glossary links.
The information in B is additional to and subsidiary to that in A.
Annotation is used by one person to write the equivalent of "margin notes" or other criticism on another's document, for example.
Example: The relationship between a newsgroup and its articles.
REPLY Similar to Annotation, but there is no suggestion that B is subsidiary to A: A and B are on equal footings.
Example: The relationship between a mail message and its reply, a news article and its reply.
EMBED If this link is followed, the node at the end of it is embedded into the display of the source document.
PRECEDES In an ordered structure defined by the author, A precedes B, B is followed by A.
Any document may only have one link of this relationship, and/or one link of the reverse relationship.
Note: May be used to control navigational aids, generate printed material, etc. In conjunction with " subdocument ", may be used to define a tree such as a printed book made of hypertext document. The document can only have one such tree.
SUBDOCUMENT B is a lower part in the author's hierarchy to A. Acyclic. See also Precedes .
PRESENT Whenever A is presented, B must also be presented. This implies that whenever A is retrieved, B must also be retrieved.
When the link is followed, the node B should be searched rather than presented. That is, where the client software allows it, the user should immediately be presented with a search panel and prompted for text. The search is then performed without an intermediate retrieval or presentation of the node B
SUPERSEDES B is a previous version of A.
HISTORY B is a list of versions of A
A link reverse link must exist from B to A and to all other known versions of A.
Relationships about subjects of documents
These relationships convey semantics about objects described by documents, rather than the documents themselves.
INCLUDES A includes B, B is part of A. For example, a person described by document A is a part of the group described by document B.
MADE Person (etc) described by node A is author of, or is responsible for B
This information can be used for protection, and informing authors of interest, for sending mail to authors, etc.
INTERESTED Person (etc) described by A is interested in node B.
This information can be used for notification of changes.
Typically, this is a request that, when object B changes in some way, a new link is made to object A.
The phrase "object B changes" may be interpreted narrowly (as
"B itself changes") or widely (as "B or anythink linked to it or
related to it closely changes").The amount of change considered
worth notifying people about is also subject to interpretation,
varying from bit changes in the source to a "new edition" statement
REGISTRATION AUTHORITY The HTTP Registration Authority is responsible for maintaining lists of:
Relationship names for link and anchor elements
It is proposed that the Internet Assigned Numbers Authority or their successors take this role.
Unregistered values may be used for experimental purposes if they are start with "X-".
SGML ISO 8879:1986, Information Processing Text and Office Systems Standard Generalized Markup Language (SGML).
sgmls an SGML parser by James Clark <email@example.com> derived from the ARCSGML parser materials which were written by Charles F. Goldfarb. The source is available on the ifi.uio.no FTP server in the directory /pub/SGML/SGMLS .
WWWThe World-Wide Web , a global information initiative. For bootstrap information, telnet info.cern.ch or find documents by ftp://info.cern.ch/pub/www/doc
Universal Resource Locators. RFCxxx. Currently available by anonymous FTP from info.cern.ch in /pub/ietf.
This document was prepared with the help and advice of many people across the net. Dan Connolly prepared the DTD and the section on HTML and SGML whilst with Convex Computer Corporation of 3000 Waterview Parkway Richardson, TX 75083. He is now with Atrium Technology Inc., and is not a current editor of the document.
Tim Berners-Lee AddressCERN 1211 Geneva 23 Switzerland
Telephone:+41(22)767 3755 Fax:+41(22)767 7155 email: firstname.lastname@example.org
Daniel Connolly Address: Atrium Technologies, Inc. 5000 Plaza on the Lake, Suite 275 Austin, TX 78746 USA email: email@example.com