HTML Reference Manual - Massey University PDF
Preview HTML Reference Manual - Massey University
Massey University Computing Services HTML Reference Manual HTML Reference Manual Index Introduction Conformance General Syntax Comments A, ABBREV, ACRONYM, ADDRESS, AU, B, BANNER, BASE, BASEFONT, BIG, BLINK, BLOCKQUOTE, BODY, BQ, BR, CAPTION, CENTER, CITE, CODE, CREDIT, DD, DEL, DFN, DIR, DIV, DL, DT, EM, FN, FIG, FONT, FORM, H1, H2, H3, H4, H5, H6, HEAD, HP, HR, HTML, I, IMG, INPUT, INS, ISINDEX, KBD, LANG, LH, LI, LINK, LISTING, MENU, META, NEXTID, NOBR, NOTE, OL, OPTION, OVERLAY, P, PERSON, PLAINTEXT, PRE, Q, S, SAMP, SELECT, SMALL, STRIKE, STRONG, SUB, SUP, TAB, TABLE, TD, TEXTAREA, TH, TITLE, TR, TT, U, UL, VAR, WBR, XMP Uniform Resource Locator (URL) Special Characters Disclaimer Acknowledgements Introduction HTML is an evolving language which is used to construct documents which can be viewed by World Wide Web browsers. HTML is attempting to be standardized by the WWW consortium but that standard is also evolving. HTML is currently defined at Version 2, but the final version of the RFC has not yet been officially published. This Reference Manual will be updated to the official RFC whenever that is published. The Version 2 Specification also declared some earlier elements obsolete. There is active work on-going to finalize the specifications of a Version 3 of HTML which contains significant new features. HTML+ was a draft of the proposals for Version 3. In addition, there is some talk of an interim Version 2.1 to standardize a few of the more desired Version 3 features earlier than the expected final agreement on a Version 3. This document attempts to include most of the extensions in the current proposal for Version 3, since some Version 3 features are beginning to be implemented in some browsers at use at Sandia. (ed:Most "Elements Allowed Within..." and "Allowed In Content Of..." still need updating, as does the meanings of some new Version 3 attributes.) While this may introduce confusion by describing non-existent features, there is value in being aware of the proposed directions in this language. The inclusion of Version 3 proposals intentionally excludes the additions to handle Mathematical Expressions since this area is still in progress. For further information about Version 3, see Acknowledgements. Not all browsers implement all features of Version 2. In addition, some browsers define and handle their own extensions. A browser is supposed to ignore any element or attribute of the http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (1 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual language that it is not designed to handle. Conformance As of the IETF HTML BOF of 26 July 1994, the Version 2 Standard Specification defined five levels of conformance of the HTML Language elements. Browsers can choose (and declare) what level of conformance they fulfill. Level 0 Mandatory. Heading, lists, anchors, etc. (A text only browser is expected to have Level 0 conformance.) Level 1 Images, Emphasis Level 2 Forms, Character Definitions Level 3 Tables, Figures, etc. (proposed in Version 3) Level 4 Mathematical formulae (proposed in Version 3, not existing practice, not yet included in this reference) General Syntax HTML is an application of ISO Standard 8879:1986 -- Standard Generalized Markup Language (SGML). SGML is a system for defining structured document types, and markup languages to represent instances of those document types. HTML is one such markup language. Its syntax follows the syntax of SGML. An HTML file is an ASCII file of text which also includes instructions to a browser, mostly about displaying the text. To formally identify the file as containing HTML elements, the beginning of the file should contain a line in SGML syntax identifying the version of HTML being used. For HTML Version 2.0, this line is <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> Sandia Requirements The SGML specification line identifying the file as HTML is required before the <HTML> element in the file. It should either specify the version number of HTML to which the file conforms by using a line like the one above, or simply specify that the file is HTML by using the line: <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"> Unless explicitly instructed otherwise, the browser normally treats all white space that is not a blank (e.g. tabs, end-of-line characters, etc.) as a single blank, and collapses multiple white space to a single blank. The browser instructions consist of HTML elements which are HTML element names, optionally followed by HTML attributes, all surrounded by "<" and ">" Attributes may be followed by an equals sign and some "value". White space is allowed around the equals sign. The standard requires that the "value" must be surrounded by single or double quotes, but many browsers do not enforce this syntax. The maximum length of "value" (after parsing) is defined as 1024 characters. Most HTML elements are designed to surround some content, usually text, and thus have both a beginning and ending tag. The ending tag is simply the element name preceded by a "/" all surrounded by "<" and ">" HTML names must begin with a letter and are followed by up to 33 letters, digits, periods, or hyphens. The standard defines the HTML names in upper case, but (except for Special Characters) browsers are supposed to ignore the case of HTML names. http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (2 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual Comments Description To include comments in an HTML document that will be ignored by the HTML browser, surround them with <!-- and -->. After the beginning comment delimiter, all text up to the next occurrence of --> is ignored. Hence comments cannot be nested. White space is allowed between the closing -- and >, but not between the opening <! and --. Minimum Attributes <!--characters... --> Common Usage <!-- characters... characters... --> Variations Not all browsers will properly handle HTML elements (i.e. an "<") inside of a comment. Some browsers will treat as comments any element that begins with "<!" and not require the two dashes at the beginning "<!--" or the end "-->" of the commented text. This syntax is actually SGML, and the browser is simply ignoring unrecognized SGML commands. Such browsers will terminate this "comment" upon the first occurance of a ">". Some browsers prohibit the double dash "--" sequence from appearing anywhere within the commented text except at the end. Version 2 specifies the double dash at beginning and end as required. A few early browsers recognized an element <comment> </comment>. The Version 2 specification delcares this element obsolete. Version 2 is proposing to add the SGML comment syntax to HTML elements. This proposal would begin a comment with a double dash encountered inside any HTML element (but not inside quotes), and treat everything as comments (including any ">", "<", or quote character) until the next occuring double dash. Such syntax would allow HTML elements within a comment. A Description The A element brackets (or anchors) a piece of text (and/or image) which is identified as a hypertext link. The A element must have either an HREF attribute or a NAME attribute. The HREF attribute identifies a destination URL, and the bracketed text is rendered as a hypertext link to the URL. Browsers will display the contents of an A element with an HREF attribute in a special manner to indicate that if the contents are selected, the browser will execute that hypertext link. The NAME attribute identifies a destination tag, and the bracketed text is thereby identified as an available hypertext target within this document. Browsers do not display the contents of an A element with a NAME attribute in any special way. However, an A element with an HREF attribute can now be constructed by using the document URL suffixed with #name. This will load the document, but will position the display starting at the location of this NAME tag. An A element with an HREF attribute can also be constructed to jump directly to this destination tag within the same document by a URL consisting solely of #name The presence of REL=relation in document A with HREF to document/object B identifies a relationship that B has to A that A recognizes/authorizes/verifies. The presence of REV=relation of the identical relation in document B with HREF to document/object A identifies a desired/expected/claimed relationship that B has to A, but must be verified by checking with A. Minimum Attributes <A HREF="..." >characters... </A> or http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (3 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual <A NAME="..." >characters... </A> All Possible Attributes <A HREF="..." NAME="..." REL="..." REV="..." URN="..." TITLE="..." METHODS="..." ID="..." LANG="..." CLASS="..." MD="..." SHAPE="...">characters... </A> Elements Allowed Within... <IMG> <BR> <EM> <STRONG> <CODE> <SAMP> <KBD> <VAR> <CITE> <TT> <B> <I> Allowed In Content Of... <ADDRESS> <B> <CITE> <CODE> <DD> <DT> <EM> <H1> <H2> <H3> <H4> <H5> <H6> <I> <KBD> <LI> <P> <PRE> <SAMP> <STRONG> <TT> <VAR> Variations HTML+ and Version 3 propose changing the NAME attribute to ID and adding an ID attribute for various elements including the paragraph and heading elements. Version 3 specifically identifies NAME as obsolete and replaced by ID. At present REV and REL are rarely used or supported, and are Level 1 attributes, but are of growing interest to automated document environments. These relationships are more commonly identified in the HEAD of the document using the LINK element. REL and REV are a comma-separated set of relationship(s) of the HREF link. These relationships and their semantics are registered with the HTML authority. Examples are UseIndex, UseGlossary, Annotation, Reply, Embed, Precedes, Subdocument, Present, Search, Supersedes, History, Made, Owns, Approves, Supports, Refutes, Includes, Interested. URN is for a Universal Resource Number, and is not currently used or supported, and is a Level 1 attribute. TITLE is little used or supported, and is a Level 1 attribute, but is expected to be the title of the HREF document. METHODS is little used or supported, but is expected to be a comma-separated list of HTTP METHODS supported by the object and accessible to the user. LANG, CLASS, and MD are the general attributes proposed by Version 3. SHAPE is proposed by Version 3 to provide a mechanism to define multiple A elements and corresponding "hotzones" within the proposed FIG element, to perform the equivalent function of ISMAP without the need for writing a responding cgi-bin program. A is a Level 0 element. ABBREV Description The ABBREV element changes the character rendering of the contents of the element to logically represent abbreviations. Minimum Attributes <ABBREV>characters... </ABBREV> All Possible Attributes <ABBREV ID="..." LANG="..." CLASS="...">characters... </ABBREV> Elements Allowed Within... -TBD- Allowed In Content Of... -TBD- Variations The ABBREV element is a Version 3 proposed element. All character definition elements are Level 2. http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (4 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual ACRONYM Description The ACRONYM element changes the character rendering of the contents of the element to logically represent acronyms. Minimum Attributes <ACRONYM>characters... </ACRONYM> All Possible Attributes <ACRONYM ID="..." LANG="..." CLASS="...">characters... </ACRONYM> Elements Allowed Within... -TBD- Allowed In Content Of... -TBD- Variations The ACRONYM element is a Version 3 proposed element. All character definition elements are Level 2. AU Description The AU element changes the character rendering of the contents of the element to logically represent the name of an author. Minimum Attributes <AU>characters... </AU> All Possible Attributes <AU ID="..." LANG="..." CLASS="...">characters... </AU> Elements Allowed Within... -TBD- Allowed In Content Of... -TBD- Variations The AU element is a Version 3 proposed element. All character definition elements are Level 2. ADDRESS Description The ADDRESS element defines a separated multi-line set of text to be rendered for address information. Minimum Attributes <ADDRESS>characters... </ADDRESS> All Possible Attributes <ADDRESS ID="..." LANG="..." CLASS="..." CLEAR=left|right|all|"..." NOWRAP>characters... </ADDRESS> Elements Allowed Within... http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (5 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual <A> <IMG> <BR> <EM> <STRONG> <CODE> <SAMP> <KBD> <VAR> <CITE> <TT> <B> <I> <P> Allowed In Content Of... <BLOCKQUOTE> <BODY> <FORM> Variations ADDRESS text is typically rendered in italics. The ID, LANG, CLASS, CLEAR, and NOWRAP attributes are proposed in Version 3. ADDRESS is a Level 0 element. Sandia Requirements An ADDRESS element is required to identify a "point-of-contact". For details, see the Sandia Requirements. B Description The B element changes the physical rendering of the contents of the element to a bold font. Minimum Attributes <B>characters... </B> All Possible Attributes <B ID="..." LANG="..." CLASS="...">characters... </B> Elements Allowed Within... <A> <IMG> <BR> <EM> <STRONG> <CODE> <SAMP> <KBD> <VAR> <CITE> <TT> <B> <I> Allowed In Content Of... <A> <ADDRESS> <B> <CITE> <CODE> <DD> <DT> <EM> <H1> <H2> <H3> <H4> <H5> <H6> <I> <KBD> <LI> <P> <PRE> <SAMP> <STRONG> <TT> <VAR> Variations Browsers who do not have bold may render in some other manner. The ID, LANG, and CLASS attributes are proposed in Version 3. All character definition elements are Level 2. BANNER Description The BANNER element is proposed for corporate logos, navigation aids, disclaimers and other information which shouldn't be scrolled with the rest of the document. Minimum Attributes <BANNER>characters... </BANNER> All Possible Attributes <BANNER ID="..." LANG="..." CLASS="...">characters... </BANNER> Elements Allowed Within... -TBD- Allowed In Content Of... <BODY> Variations This is a proposed Version 3 element. http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (6 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual BASE Description The BASE element provides the URL base to be used for any relative URL links in this document. It must be a complete file name, and is usually the original URL of this document. If this file is moved, having the BASE set to the original URL eliminates the need to also move all the documents which are identified by relative URL links in this document. Minimum Attributes <BASE HREF="..."> All Possible Attributes <BASE HREF="..."> Elements Allowed Within... Allowed In Content Of... <HEAD> Variations This is a Level 0 element. BASEFONT Description Change the document base font size to one of the seven defined sizes. The default is 3. Minimum Attributes <BASEFONT SIZE=1|2|3|4|5|6|7> All Possible Attributes <BASEFONT SIZE=1|2|3|4|5|6|7> Elements Allowed Within... -TBD- Allowed In Content Of... -TBD- Variations The BASEFONT element is a Netscape extension. BIG Description The BIG element changes the physical rendering of the contents of the element to a bigger font than normal text, if practical. Minimum Attributes <BIG>characters... </BIG> All Possible Attributes <BIG ID="..." LANG="..." CLASS="...">characters... </BIG> Elements Allowed Within... -TBD- http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (7 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual Allowed In Content Of... -TBD- Variations The BIG element is proposed in Version 3. All character definition elements are Level 2. BLINK Description The BLINK element changes the physical rendering of the contents of the element to a blinking font. Minimum Attributes <BLINK>characters... </BLINK> All Possible Attributes <BLINK>characters... </BLINK> Elements Allowed Within... -TBD- Allowed In Content Of... -TBD- Variations This element is not listed in the standard, and many browsers ignore this element. Many users find the use of this element annoying. It should be restricted to short term use for new information. Netscape 1.1N permits users to disable the rendering of this element. BLOCKQUOTE Description The BLOCKQUOTE element defines a separated multi-line set of text to be rendered as quoted text. Minimum Attributes <BLOCKQUOTE> </BLOCKQUOTE> All Possible Attributes <BLOCKQUOTE> </BLOCKQUOTE> Elements Allowed Within... <H1> <H2> <H3> <H4> <H5> <H6> <P> <UL> <OL> <DIR> <MENU> <DL> <PRE> <BLOCKQUOTE> <FORM> <ISINDEX> <HR> <ADDRESS> Allowed In Content Of... <BLOCKQUOTE> <BODY> <DD> <FORM> <LI> Variations The contents of the BLOCKQUOTE element is typically rendered slightly indented both left and right, and/or italic font. Early browsers displayed the contents with a vertical line of ">" characters down the left margin to indicate quotation in the Internet mail style. Version 3 proposes replacing the BLOCKQUOTE element with the BQ element. BLOCKQUOTE is a Level 0 element. http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (8 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual BODY Description The BODY element contains all the content of the document, as opposed to the HEAD, which contains information about the document. All displayable elements should be within the content of the BODY. Minimum Attributes All Possible Attributes <BODY ID="..." LANG="..." CLASS="..." BACKGROUND="..." BGCOLOR="#rrggbb" TEXT="#rrggbb" LINK="#rrggbb" VLINK="#rrggbb" ALINK="#rrggbb"> </BODY> Elements Allowed Within... <H1> <H2> <H3> <H4> <H5> <H6> <P> <UL> <OL> <DIR> <MENU> <DL> <PRE> <BLOCKQUOTE> <FORM> <ISINDEX> <HR> <ADDRESS> Allowed In Content Of... <HTML> Variations The HTML, HEAD, and BODY elements were introduced with Version 2, and are currently optional, but are considered Level 0 elements by the Version 2 standard. Version 3 proposes the attributes ID, LANG, CLASS, and BACKGROUND. Netscape 1.1 includes the BACKGROUND attribute, which is a URL to point to an image to be reproduced to fill the background of the document. The BGCOLOR, LINK, VLINK, and ALINK attributes are Netscape 1.1 extensions. Sandia Requirements The HTML, HEAD and BODY elements are required. BQ Description The BQ element defines a multi-line set of text to be rendered as quoted text. The content of the BQ element may optionally contain the CREDIT element. Minimum Attributes <BQ> </BQ> All Possible Attributes <BQ ID="..." LANG="..." CLASS="..." CLEAR=left|right|all|"..." NOWRAP> </BQ> Elements Allowed Within... <CREDIT> -others TBD- Allowed In Content Of... <BQ> -others TBD- Variations The BQ element is proposed in Version 3 as a replacement for the BLOCKQUOTE element. Version 3 does not indicate the typical rendering of the contents of the BQ element, but does indicate that it may not imply text separation. http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (9 of 48) [2/04/2001 14:27:54] Massey University Computing Services HTML Reference Manual BR Description The BR element breaks for a new line, but does not produce separation of text. Minimum Attributes <BR> All Possible Attributes <BR CLEAR=left|right|all|"..." ID="..." LANG="..." CLASS="..."> Elements Allowed Within... Allowed In Content Of... <A> <ADDRESS> <B> <CITE> <CODE> <DD> <DT> <EM> <H1> <H2> <H3> <H4> <H5> <H6> <I> <KBD> <LI> <P> <PRE> <SAMP> <STRONG> <TT> <VAR> Variations The CLEAR attribute is a Netscape extension and was added to force the line break to clear possible floating graphic images. Version 3 includes CLEAR, and proposes the remaining attributes. The BR element is Level 0. CAPTION Description The CAPTION element is used to label a table or figure. Minimum Attributes <CAPTION>characters... </CAPTION> All Possible Attributes <CAPTION ALIGN=top|bottom|left|right ID="..." LANG="..." CLASS="...">characters... </CAPTION> Elements Allowed Within... -TBD- Allowed In Content Of... <FIG> <TABLE> Variations The CAPTION element is proposed in Version 3. There is some discussion that the only values that make sense for the ALIGN attribute when CAPTION is used in the contents of the TABLE element are top|bottom This element is an extension in Netscape 1.1. CENTER Description All contents within the CENTER element is to be centered between the current left and right margin. Minimum Attributes <CENTER>characters... </CENTER> All Possible Attributes <CENTER>characters... </CENTER> Elements Allowed Within... -TBD- http://www.massey.ac.nz/%7Ewwits/services/www/wwwdev/html_reference.html (10 of 48) [2/04/2001 14:27:55]
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