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A, ABBREV, ACRONYM, ADDRESS, APP, APPLET, AREA, AU, B, BANNER, BASE, BASEFONT, BDO, BGSOUND, BIG, BLINK, BLOCKQUOTE, BODY, BQ, BR, CAPTION, CENTER, CITE, CODE, COL, COLGROUP, CREDIT, DD, DEL, DFN, DIR, DIV, DL, DT, EM, EMBED, FN, FIG, FONT, FORM, FRAME, FRAMESET, H1, H2, H3, H4, H5, H6, HEAD, HP, HR, HTML, I, IMG, INPUT, INS, ISINDEX, KBD, LANG, LH, LI, LINK, LISTING, MAP, MARQUEE, MENU, META, NEXTID, NOBR, NOEMBED, NOFRAMES, NOTE, OL, OPTION, OVERLAY, P, PARAM, PERSON, PLAINTEXT, PRE, Q, S, SAMP, SELECT, SMALL, SPAN, STRIKE, STRONG, SUB, SUP, TAB, TABLE, TBODY, TD, TEXTAREA, TFOOT, TH, THEAD, TITLE, TR, TT, U, UL, VAR, WBR, XMP

Element Groups

To shorten the lists in each element to describe the "Elements Allowed Within..." and "Allowed In Content Of..." various elements are defined by RFC 1866 as members of a group. These group names are used throughout the RFC 1866. Since group names can be defined to contain other group names, this mechanism makes nesting and recursion more obvious. Note that these element groups only deal with entities defined in RFC 1866 and do not include any of the entities in proposed extensions.

block: Contains the groups block.forms, list, preformattedand the entities DL and P
The tables proposal defines the TABLE element as a member of this group block
block.forms: Contains the entities BLOCKQUOTE, FORMand ISINDEX
body.content: Is allowed to contain the groups block, heading, textand the entities HR and ADDRESS
It is recommended that it contain only the groups block, headingand the entities HR, ADDRESSand IMG This recommended change in the members of this group means that all text within a body should be enclosed in some kind of block. This means that
<h1>Heading<h1>
<p>Text ...
is recommended over
<h1>Heading<h1>
Text ...
font: Contains the entities TT, Band I
heading: Contains the entities H1, H2, H3, H4, H5and H6
list: Contains the entities UL, OL, DIRand MENU
Note that it does not contain DL which is identified separately.
phrase: Contains the entities EM, STRONG, CODE, SAMP, KBD, VARand CITE
preformated: Is allowed to contain the entities PRE, XMPand LISTING
The last two entities are deprecated and this group should contain only the entity PRE
text: Contains the groups phrase and font and the entities A, IMG and BR and parsed character data. Parsed character data is any valid character data after the data has been parsed and all special character entities have been replaced with their character data.
The internationalization proposal also includes in group text the entities BDO, Q, SPAN, SUB, SUP

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; <A NAME="..." >characters... </A>
All Possible Attributes: <A HREF="..." NAME="..." REL="..." REV="..." URN="..." TITLE="..." METHODS="..." LANG="..." DIR=ltr|rtl CHARSET="..." ID="..." CLASS="..." MD="..." TARGET="..." SHAPE="...">characters... </A>
Elements Allowed Within...: members of groups heading text but not element <A>
Allowed In Content Of...: Any element that permits members of group text
Variations: The LANG, DIR and CHARSET attributes are introduced with the internationalization proposal. The CHARSET attribute is a hint as to the expected character set used by the hyperlink. Earlier proposals suggest changing the NAME attribute to ID, declaring the NAME attribute as obsolete, and adding an ID attribute for various elements including the paragraph and heading elements. With the ID, MD, and CLASS attributes as part of the style sheet proposal, this is likely to change. 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 can be either a comma-separated or white space separated set of relationship(s) of the HREF link. One proposal suggests that comma imply "or" and white space imply "and" for a list of values. These relationships and their semantics were originally proposed to be registered with an HTML authority, which was described at http://www.w3.org/hypertext/WWW/MarkUp/RegistrationAuthority.html, but that link no longer responds. The entire topic of link relationships is under active discussion and change. Early examples of relationship names 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. RFC 1866 describes it as a preferred, more persistent identifier than the value of HREF. TITLE is little used or supported, and is a Level 1 attribute, but is expected to be the title of the HREF document. RFC 1866 suggests TITLE can be displayed as a margin note or on a small box while the mouse is over the anchor. (ed. I am unaware of any browser that has implemented this feature.) METHODS is little used or supported, but is expected to be a white-space-separated list of HTTP METHODS supported by the object and accessible to the user. RFC 1866 suggests that the content of the A element may be rendered differently depending upon the HTTP method. TARGET is a Netscape 2.0 extension to define a window name for use by the retrieved hyperlink. If the named window is not already open, Netscape 2.0 will open a new window and assign it that name. See also the FRAME element for naming a window. SHAPE is proposed 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. For an alternate proposal, see the MAP element. 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 LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </ABBREV>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The ABBREV element is a Version 3 proposed element. All character definition elements are Level 2.

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 LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </ACRONYM>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The ACRONYM 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 LANG="..." DIR=ltr|rtl ALIGN=center|left|right|justify ID="..." CLASS="..." CLEAR=left|right|all|"..." NOWRAP>characters... </ADDRESS>
Elements Allowed Within...: members of group text or element <P>
Allowed In Content Of...: Any element that permits members of group body.content
Variations: ADDRESS text is typically rendered in italics, and may be indented. The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify The 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.

APP

See the element APPLET

APPLET

Description: The APPLET element replaced the APP element as the mechanism to identify and invoke a JAVA(tm) application. A browser that understands this element will ignore everything in the content of the APPLET element except the PARAM elements. Browsers that do not understand this element should ignore it and the PARAM elements and instead process the content of the element. Thus the content is the alternate HTML if the application is not invoked. CODE is the name of the file that contains the compiled Applet subclass. This name is relative to the base URL of the applet and cannot be an absolute URL. WIDTH and HEIGHT give the initial width and height (in pixels) of the applet display area. CODEBASE specifies the base URL of the applet. ALT specifies parsed character data to be displayed if the brower understands the APPLET tag but can't/won't run them. NAME specifies a name for the applet instance, which allows applets on the same page to commuicate with each other. ALIGN specifies the display alignment. VSPACE and HSPACE specify the reserved space around the applet (in pixels).
Minimum Attributes: <APPLET CODE="..." WIDTH="..." HEIGHT="...">characters... </APPLET>
All Possible Attributes: <APPLET CODE="..." WIDTH="..." HEIGHT="..." CODEBASE="..." ALT="..." NAME="..." ALIGN=left|right|top|texttop|middle|absmiddle|baseline|bottom|absbottom VSPACE="..." HSPACE="...">characters... </APPLET>
Elements Allowed Within...: <PARAM> and any other elements which would have been allowed at this point in the document.
Allowed In Content Of...: -In progress, to be determined-
Variations: The APPLET element is a proposed extension for JAVA(tm) applications, and is a Netscape 2.0 extension.

AREA

Description: The AREA element specifies a single area of an image which, if selected, will link to the hyperlink identified by HREF. If multiple AREA elements in the same MAP define overlapping areas, the first encountered takes precedence.
Minimum Attributes: <AREA COORDS="...">
All Possible Attributes: <AREA COORDS="..." SHAPE=rect|circle|polygon HREF="..." NOHREF ALT="...">
Elements Allowed Within...: AREA has no end tag and therefore has no content.
Allowed In Content Of...: <MAP>
Variations: The AREA element is part of a proposed enhancement to provide client-side image maps. COORDS describes the position of an area (in pixels) of the image in comma-separated x,y coordinates where the upper-left corner is "0,0". For SHAPE=rect (the default), it is "left,top,right,bottom". For SHAPE=circle, it is "center_x,center_y,radius". For SHAPE=polygon, it is successive x,y vertices of the polygon. If the first and last coordinates are not the same, then a segment is inferred to close the polygon. The NOHREF indicates that this region should generate no links. The ALT attribute specifies optional parsed character data to describe the area which could be displayed by a text-only browser as a substitute for the image. AREA is an extension in Netscape 2.0, but the only SHAPE recognized is "rect", and ALT is not defined.

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 LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </AU>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The AU element is a Version 3 proposed element. All character definition elements are Level 2.

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 LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </B>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group font
Variations: Browsers who do not have bold may render in some other manner. RFC 1866 states that <B> content must be rendered as distinct from <I> content. The LANG and DIR attributes are introduced with the internationalization proposal. 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 LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </BANNER>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: <BODY>
Variations: This is a proposed Version 3 element.

BASE

Description: The BASE element provides the absolute 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="..." TARGET="...">
Elements Allowed Within...
Allowed In Content Of...: <HEAD>
Variations: This is a Level 0 element. Netscape 2.0 defines the TARGET attribute to define a default named target window for every link in a document that does not have an explicit TARGET attribute.

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...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The BASEFONT element is a Netscape extension.

BDO

Description: The BDO element is a directional override feature needed to deal with unusual pieces of text in which directionality cannot be resolved from context in an unambiguous fashion. It requires the DIR attribute. The meaning of DIR is different on BDO than on inline text markup elements. For BDO the DIR attribute is a bidi override, forcing the directionnality of even those characters that have strong directionnality. On inline elements, DIR indicates a new directional embedding level, affecting mostly the neutrals and the overall layout.
Minimum Attributes: <BDO DIR=ltr|rtl>characters... </BDO>
All Possible Attributes: <BDO DIR=ltr|rtl LANG="...">characters... </BDO>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group text
Variations: The BDO element is a proposed element as part of the enhancement to deal with internationalization of HTML.

BGSOUND

Description: The BGSOUND element will cause an audio file to be presented as background to the document.
Minimum Attributes: <BGSOUND SRC="...">
All Possible Attributes: <BGSOUND SRC="..." LOOP="...">
Elements Allowed Within...: The BGSOUND element is defined as having no content.
Allowed In Content Of...: -In progress, to be determined-
Variations: The BGSOUND element is a MS Internet Explorer 2.0 enhancement. SRC specifies the URL of the audio file to be played. LOOP specifies how many times the sound will be displayed while the HTML document is displayed, and can either be a number or the string "infinite". The default for LOOP is one. Considerable opposition to the use of this element has been expressed on the Web, especially the use of LOOP=infinite, since users currently have no way to disable the audio.

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 LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </BIG>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The BIG element is proposed in Version 3, and is implemented as a Netscape 2.0 enhancement. 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...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: This element is a Netscape 1.1 enhancement 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 LANG="..." DIR=ltr|rtl ALIGN=center|left|right|justify> </BLOCKQUOTE>
Elements Allowed Within...: members of group body.content
Allowed In Content Of...: Any element that permits members of group block.forms
Variations: RFC 1866 states the contents of the BLOCKQUOTE element is typically rendered slightly indented both left and right, and/or italic font. It also states that a single-font browser rendering may display the contents with a vertical line of ">" characters down the left margin to indicate quotation in the Internet mail style. The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify Version 3 proposes replacing the BLOCKQUOTE element with the BQ element. BLOCKQUOTE is a Level 0 element.

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 LANG="..." DIR=ltr|rtl ID="..." CLASS="..." BACKGROUND="..." BGCOLOR="..." BGPROPERTIES=fixed TEXT="#rrggbb" LINK="#rrggbb" VLINK="#rrggbb" ALINK="#rrggbb"> </BODY>
Elements Allowed Within...: members of group body.content
Allowed In Content Of...: <HTML>
Variations: The HTML, HEAD, and BODY elements were introduced with RFC 1866, and are currently optional, but are considered Level 0 elements. The LANG and DIR attributes are introduced with the internationalization proposal. Version 3 proposes the attribute BACKGROUND. Netscape 1.1 and MS Internet Explorer 2.0 include the BACKGROUND attribute, which is a URL to point to an image to be reproduced to fill the background of the document. Netscape 1.1 and MS Internet Explorer 2.0 both document the BGCOLOR extension. Netscape requires an "#rrggbb" number, while Internet Explorer also accepts the following color names: Black, Maroon, Green, Olive, Navy, Purple, Teal, Gray, Silver, Red, Lime, Yellow, Blue, Fuchsia, Aqua, White. The TEXT, LINK, VLINK, and ALINK attributes are Netscape 1.1 extensions, and also appear to work with MS Internet Explorer 2.0. BGPROPERTIES is an MS Internet Explorer 2.0 extension and currently only accepts the value of "fixed" which provides a watermark (non-scrolling) background image.
Sandia Requirements: The HTML, HEAD and BODY elements are required.

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 LANG="..." DIR=ltr|rtl ID="..." CLASS="..." CLEAR=left|right|all|"..." NOWRAP> </BQ>
Elements Allowed Within...: <CREDIT>-others to be determined-
Allowed In Content Of...: <BQ>-others to be determined-
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.

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="..." CLASS="...">
Elements Allowed Within...: The BR element is defined as having no content.
Allowed In Content Of...: Any element that permits members of group text
Variations: The CLEAR attribute is a Netscape 1.1 extension and was added to force the line break to clear possible floating graphic images. The standard tables proposal expects the presence of this attribute since it expects text to flow around a table, if possible, but does not standardize the attribute's existence as part of the proposal. 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. The ALIGN attribute specifies on which outside edge to place the caption.
Minimum Attributes: <CAPTION>characters... </CAPTION>
All Possible Attributes: <CAPTION ALIGN=top|bottom|left|right LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </CAPTION>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: <FIG> <TABLE>
Variations: The CAPTION element was originally proposed in Version 3 and is part of the current table proposal. 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...: -In progress, to be determined-
Allowed In Content Of...: <A>-In progress, to be determined-
Variations: The CENTER element is a Netscape 1.1 extension. It was provided as an alternative to the HTML+ and Version 3 ALIGN="center" proposed new attribute for all the text block elements such as the <P> paragraph and <H?> header elements and the new <DIV> element. Both RFC 1866 and the current Version 3 specification only include the ALIGN attribute, not the CENTER element, and Netscape 2.0 has added the ALIGN="center" attribute.

CITE

Description: The CITE element changes the character rendering of the contents of the element to logically represent a citation.
Minimum Attributes: <CITE>characters... </CITE>
All Possible Attributes: <CITE LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </CITE>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group phrase
Variations: This is typically rendered in italics. The LANG and DIR attributes are introduced with the internationalization proposal. All character definition elements are Level 2.

CODE

Description: The CODE element changes the character rendering of the contents of the element to logically represent computer code. It is intended for short words or phrases. PRE is recommended for multiple-line listings.
Minimum Attributes: <CODE>characters... </CODE>
All Possible Attributes: <CODE LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </CODE>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group phrase
Variations: This is usually rendered in a fixed-width font. The LANG and DIR attributes are introduced with the internationalization proposal. All character definition elements are Level 2.

COL

Description: The COL element specifies column based defaults for table properties.
Minimum Attributes: <COL>
All Possible Attributes: <COL LANG="..." DIR=ltr|rtl ID="..." CLASS="..." SPAN=nn WIDTH="..." ALIGN=left|center|right|justify|char CHAR="." CHAROFF="..." VALIGN=top|middle|bottom|baseline>
Elements Allowed Within...: COL has no end element, therefore it has no content.
Allowed In Content Of...: COLGROUP TABLE
Variations: The COL element is part of the new proposed standard tables structure. It is not widely implemented in existing browsers. The order of placement of a series of COL elements within the TABLE content (or within a COLGROUP) is significant, and describes the columns in the TABLE DIR presentation order, first to last. SPAN is a positive integer that specifies how many columns this element applies to, defaulting to one. SPAN=0 implies all columns from the current column up to and including the last column. WIDTH is a decimal number which specifies the width of each column in the span. The default units is pixels, but may be specified by a suffix on the number. The standard defined units suffixes include: pt=points, pi=picas, in=inches, cm=centimeters, mm=millimeters, em=em units, px=screen pixels. In addition, the special suffix of an asterisk may be used to specify a number to be used as a multiplier of a "standard" column width. This is used to specify the widths of columns proportionately relative to each other. If a number does not accompany the asterisk it defaults to one. Specifying WIDTH="0*" forces the column to its minimum width. ALIGN and VALIGN define the alignment of text within a table cell. If ALIGN=char, CHAR specifies the alignment character which defaults to the decimal point for the current language. CHAROFF is a decimal number that specifies the offset for the alignment character from the beginning of the table cell in the DIR direction. Units may be specified using the standard defined units suffixes plus the special suffix of the percent sign indicating the percentage of offset within the cell from the beginning of the cell.

COLGROUP

Description: The COLGROUP element defines a group of one or more columns and specifies the defaults for all the columns in this group.
Minimum Attributes: <COLGROUP>
All Possible Attributes: <COLGROUP LANG="..." DIR=ltr|rtl ALIGN=left|center|right|justify|char ID="..." CLASS="..." CHAR="." CHAROFF="..." VALIGN=top|middle|bottom|baseline>characters... </COLGROUP>
Elements Allowed Within...: COL
Allowed In Content Of...: TABLE
Variations: The COLGROUP element is part of the new proposed standard tables structure. It is not widely implemented in existing browsers. The end tag is optional and is inferred when a new COLGROUP is encountered or the THEAD or TBODY element of TABLE. The order of placement of a series of COLGROUP elements within the TABLE content is significant, and describes the columns in the TABLE DIR presentation order, first to last. ALIGN and VALIGN define the alignment of text within a table cell. If ALIGN=char, CHAR specifies the alignment character which defaults to the decimal point for the current language. CHAROFF is a decimal number that specifies the offset for the alignment character from the beginning of the table cell in the DIR direction. The default units is pixels, but may be specified by a suffix on the number. The standard defined units suffixes include: pt=points, pi=picas, in=inches, cm=centimeters, mm=millimeters, em=em units, px=screen pixels. In addition, the special suffix of the percent sign may be used to indicate the percentage of offset within the cell from the beginning of the cell.

CREDIT

Description: The CREDIT element is used to name the source of a block quotation or figure.
Minimum Attributes: <CREDIT>characters... </CREDIT>
All Possible Attributes: <CREDIT LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </CREDIT>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: <BQ> <FIG>
Variations: The CREDIT element is proposed in Version 3. Version 3 does not indicate the typical rendering for the contents of the CREDIT element, nor whether that rendering should be different or separated from the enclosing block quotation or figure.

Description: The DD element identifies the separated multi-line definition item in a DL definition list. In a DL list a DD should always be preceded by at least one DT element.
Minimum Attributes: <DD>characters...
All Possible Attributes: <DD LANG="..." DIR=ltr|rtl>characters... </DD>
Elements Allowed Within...: members of groups block text
Allowed In Content Of...: <DL>
Variations: This is typically rendered as normal text, indented. Most browsers assume that the contents of the element ends when it encounters a <DT> or another <DD> or the </DL> element to end the list, and thus do not require the ending tag. The LANG and DIR attributes are introduced with the internationalization proposal. All list elements are Level 0.

DEL

Description: The DEL element changes the character rendering of the contents of the element to logically represent deleted text, for instance in modifications in legal documents.
Minimum Attributes: <DEL>characters... </DEL>
All Possible Attributes: <DEL LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </DEL>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The DEL element is a Version 3 proposed element. While this will typically be rendered by strikethru characters, the DEL element is preferred over using the S or STRIKE elements. All character definition elements are Level 2.

DFN

Description: The DFN element changes the character rendering of the contents of the element to logically represent a defining instance of a term.
Minimum Attributes: <DFN>characters... </DFN>
All Possible Attributes: <DFN LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </DFN>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The DFN element is not widely implemented, but is usually rendered bold or bold italic. It is a Version 3 proposed element and was in an earlier Version 2 proposal. The RFC 1866 describes it and recognizes it as existing practice but does not include it in the standardized elements.

DIR

Description: The DIR element defines an unordered list consisting of a number of single-line <LI> elements.
Minimum Attributes: <DIR></DIR>
All Possible Attributes: <DIR COMPACT LANG="..." DIR=ltr|rtl ALIGN=center|left|right|justify> </DIR>
Elements Allowed Within...: element <LI> but not any member of group block
Allowed In Content Of...: Any element that permits members of group list
Variations: This list type is not commonly implemented, and is often rendered identically to UL. RFC 1866 specifies that the content of the LI element of the DIR list is usually less than 20 characters in length. These may be arranged in columns across the page, each column typically as 24 characters wide. Specifying <UL PLAIN WRAP=HORIZ> is proposed in Version 3 as a replacement for the DIR element. The exclusion in RFC 1866 of group block within DIR implies (among other things) that DIR can contain no nested lists, nor any paragraphs even though the LI element normally would allow this. Some browsers do not enforce this exclusion. The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify All list elements are Level 0.

DIV

Description: The DIV element is proposed to be used with the CLASS attribute to represent different kinds of containers, e.g. chapter, section, abstract, or appendix.
Minimum Attributes: <DIV>characters... </DIV>
All Possible Attributes: <DIV LANG="..." DIR=ltr|rtl ALIGN=left|center|right|justify ID="..." CLASS="..." NOWRAP CLEAR=left|right|all|"...">characters... </DIV>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: <BODY>
Variations: This is a proposed Version 3 element. <DIV ALIGN=center> is the proposed replacement for the non-standard CENTER element. This is a Netscape 2.0 extension but it only recognizes ALIGN=left|right|center.

Description: The DL element defines a definition list. Each item in the list is expected to have two parts, identified by the <DT> and <DD> elements.
Minimum Attributes: <DL></DL>
All Possible Attributes: <DL COMPACT LANG="..." DIR=ltr|rtl ID="..." CLASS="..." CLEAR=left|right|all|"..."> </DL>
Elements Allowed Within...: <LH><DT> <DD>
Allowed In Content Of...: Any element that permits members of group block
Variations: The COMPACT attribute suggests rendering the list in a physically compact way, but is not implemented by many browsers. RFC 1866 suggests that the attribute be used if the list items are small and/or the entire list is large, and may cause the elimination of blank lines between DT/DD pairs. The LANG and DIR attributes are introduced with the internationalization proposal. Version 3 proposes the CLEAR attribute. To obtain a specific look, it has been the practice to construct a DL with DD elements but empty or missing DT elements. Missing DT elements violates the standard. Version 3 proposes a new NOTE element as the preferred alternative to achieve the effect desired. All list elements are Level 0.

Description: The DT element identifies the separated term item in a DL definition list. Multiple DT elements may exist prior to a single DD element. In a DL list a DD should always be preceded by at least one DT element.
Minimum Attributes: <DT>characters...
All Possible Attributes: <DT LANG="..." DIR=ltr|rtl>characters... </DT>
Elements Allowed Within...: members of group text
Allowed In Content Of...: <DL>
Variations: This is typically rendered in a bold font, but not indented. Most browsers assume that the contents of the element ends when it encounters a <DD> or another <DT> or the </DL> element to end the list, and thus do not require the ending tag. The LANG and DIR attributes are introduced with the internationalization proposal. All list elements are Level 0.

Description: The EM element changes the character rendering of the contents of the element to logically emphasize the text.
Minimum Attributes: <EM>characters... </EM>
All Possible Attributes: <EM LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </EM>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group phrase
Variations: Usually rendered in italics. RFC 1866 states that <EM> content must be rendered as distinct from <STRONG> content. The LANG and DIR attributes are introduced with the internationalization proposal. All character definition elements are Level 2.

EMBED

Description: The EMBED element defines a container that allows the insertion of arbitrary objects directly into an HTML page. Embedded objects are supported by application-specific plug-ins. EMBED is defined to allow arbitrary attributes.
Minimum Attributes: <EMBED SRC="...">
All Possible Attributes: <EMBED SRC="..." HEIGHT="..." WIDTH="..." attribute_1="..." attribute_2="..." ...>characters... </EMBED>
Elements Allowed Within...: <NOEMBED>
Allowed In Content Of...: -In progress, to be determined-
Variations: The EMBED element is a Netscape 2.0 extension. Netscape gives as examples of plug-in applications: WebFX by Paper Software for viewing VRML (Virtual Reality Modeling Language) worlds, Adobe Acrobat for PDF documents, and Macromedia Director and Apple QuickTime for multimedia. Netscape's examples do not include the ending element, but their documentation does not specify what would imply the end of the EMBED content if the ending element is absent. The concept of arbitrary undefined attributes violates the underlying SGML standard of HTML. Change is expected in this element. See also the APPLET element. The Netscape documentation does not currently define the units for HEIGHT and WIDTH but examples would imply that they are pixels. The object's image will be scaled to fit the specified height/width. Embedded plug-in applications may be activated by double-clicking their image.

FIG

Description: The FIG element is an advanced form of the IMG element to define an image, with optional overlays, text elements and "hotzones", to be inserted within a document. The structure of the contents of the FIG element expects a series of optional overlay images defined by OVERLAY elements, followed by an optional CAPTION element, followed by text to be presented as an alternative to the image(s) and which may contain normal text elements as well as hypertext links defined by A elements with SHAPE attributes to identify "hotzones" on the image, finally completed by an optional CREDIT element.
Minimum Attributes: <FIG SRC="..."></FIG>
All Possible Attributes: <FIG SRC="..." LANG="..." DIR=ltr|rtl ID="..." CLASS="..." CLEAR=left|right|all|"..." NOFLOW MD="..." ALIGN=left|right|center|justify|bleedleft|bleedright WIDTH=value HEIGHT=value UNITS="..." IMAGEMAP="..."></FIG>
Elements Allowed Within...: <OVERLAY><CAPTION> <CREDIT> -In progress, to be determined- (ed: all normal markup elements?)
Allowed In Content Of...: -In progress, to be determined-
Variations: The FIG element is proposed in Version 3 as a sophisticated alternative to the IMG element, especially to enhance the capabilities of the ALT text for non-graphical presentations of HTML documents, as well as a way to accomplish the common use of the ISMAP attribute of the IMG element without the need for a responding cgi-bin program.

Description: The FN element logically identifies text to be presented as a footnote. The reference location for the footnote is expected to be an A element whose HREF attribute references the ID of the FN element.
Minimum Attributes: <FN ID="...">characters... </FN>
All Possible Attributes: <FN LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </FN>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The FN element is a Version 3 proposed element. Version 3 specifies that when practical, the browser should render the FN element as pop-up notes. Version 3 does not specify an expected rendering when the footnote text is simply displayed where it occurs in the document. However, Version 3 does state that the FN element does not imply text separation. Therefore, common practice expects that the contents of the FN element would begin with a markup element which produces separation, e.g. the P element.

FONT

Description: The FONT element changes the font size of the following characters to one of the seven defined sizes, or plus or minus from the document BASEFONT size.
Minimum Attributes: <FONT SIZE=[+|-]1|2|3|4|5|6|7>
All Possible Attributes: <FONT SIZE=[+|-]1|2|3|4|5|6|7 COLOR="..." FACE="...">
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The FONT element with the SIZE attribute is a Netscape 1.1 and MS Internet 2.0 extension. Netscape 2.0 and MS Internet Explorer 2.0 added the COLOR attribute. Netscape requires an "#rrggbb" number, while Internet Explorer also accepts the following color names: Black, Maroon, Green, Olive, Navy, Purple, Teal, Gray, Silver, Red, Lime, Yellow, Blue, Fuchsia, Aqua, White. The FACE attribute is a MS Internet Explorer 2.0 extension to specify a font style, but the permitted values are not defined.

FORM

Description: The FORM element creates a fill-out form. The browser permits the user to enter information in the fields of the form and sends this information to a cgi-bin script on a server identified as a URL by the ACTION attribute. METHOD=GET (the default) appends the input information to the ACTION URL which on most receiving systems becomes the value of the environment variable QUERY_STRING. METHOD=POST (the preferred) sends the input information in a data body which is available on stdin with the data length set in the environment variable CONTENT_LENGTH. Form data is a stream of name=value pairs separated by the & character. Each name=value pair is URL encoded, i.e. spaces are changed into the plus character and some characters are encoded into hexadecimal. At least one of the following is expected inside the FORM contents: INPUT, SELECT, TEXTAREA.
Minimum Attributes: <FORM></FORM>
All Possible Attributes: <FORM ACTION="..." METHOD=GET|POST ENCTYPE="..." LANG="..." DIR=ltr|rtl ACCEPT-CHARSET="..." SCRIPT="..."> </FORM>
Elements Allowed Within...: members of group body.contentand elements <INPUT> <SELECT> <TEXTAREA>but not element <FORM>
Allowed In Content Of...: Any element that permits members of group block.forms
Variations: The original definition of FORM only defined the default value of application/x-www-form-urlencoded for the ENCTYPE attribute. RFC 1867 adds the value of multipart/form-data for this attribute to permit a FORM to upload one or more files in addition to the FORM data. METHOD=POST is required with this value of ENCTYPE. This file upload extension is implemented in Netscape 2.0. Most current browsers only handle ACTION for the http: access type, but proposals for handling the mailto: access type are being discussed. The LANG, DIR, and ACCEPT-CHARSET attributes are introduced with the internationalization proposal. The ACCEPT-CHARSET attribute is to provide a hint as to the character set or sets that the receiving URL is prepared to handle. Version 3 proposes the SCRIPT attribute to specify a URL which contains a limited syntax script to be downloaded to the browser for execution to preprocess the FORM output before sending it to the ACTION destination. This SCRIPT proposal may change as part of the new proposals concerning APPLET and EMBED. All elements concerning FORM are Level 2.

FRAME

Description: The FRAME element defines a single frame in a frameset. The SRC attribute value is the URL of the document to be displayed in this frame. A FRAME element without a SRC is displayed as blank space. The NAME element assigns a name to the frame to be used as a target of hyperlinks. (See the A element) The SCROLLING attribute is used to define whether the frame should have a scrollbar, and defaults to the value "auto". Presence of the NORESIZE attribute prevents the frame from being resized by the user.
Minimum Attributes: <FRAME>
All Possible Attributes: <FRAME SRC="..." NAME="..." MARGINWIDTH="..." MARGINHEIGHT="..." SCROLLING=yes|no|auto NORESIZE>
Elements Allowed Within...: The FRAME element is defined as having no content.
Allowed In Content Of...: <FRAMESET>
Variations: The FRAME element is a Netscape 2.0 enhancement for defining multiple windows for viewing a document. Netscape 2.0 reserves the following values for the NAME attribute: _blank, _self, _parent, _top. These values must begin with the underbar character and have the following respective meanings: new unnamed window, load in the same window, load in the parent window (if none use self), load in the top window (if none use self). Netscape 2.0 defines the units for MARGINWIDTH and MARGINHEIGHT as pixels.

FRAMESET

Description: The FRAMESET element is used instead of the BODY element. It is used in an HTML document whose sole purpose is to define the layout of the sub-HTML documents, or Frames, that will make up the page. The ROWS and COLS values are comma-separated lists describing the row-heights and column-widths of the Frames.
Minimum Attributes: <FRAMESET>characters... </FRAMESET>
All Possible Attributes: <FRAMESET ROWS="..." COLS="...">characters... </FRAMESET>
Elements Allowed Within...: <FRAME> <FRAMESET> <NOFRAMES>
Allowed In Content Of...: <HTML>
Variations: The FRAMESET element is a Netscape 2.0 enhancement. Netscape 2.0 restricts the ROWS and COLS values to integers with an optional suffix to define the units. Default units are pixels. A percentsign suffix indicates the value is a percentage between 1 and 100. A suffix of an asterisk may be used to specify a number to be used as a multiplier of a "standard" width/height. This is used to specify the widths/heights of Frames proportionately relative to each other. If a number does not accompany the asterisk it defaults to one.

Description: The H1 element identifies text to be separated and displayed as the most prominent header.
Minimum Attributes: <H1>characters... </H1>
All Possible Attributes: <H1 LANG="..." DIR=ltr|rtl ALIGN=left|center|right|justify ID="..." CLASS="..." CLEAR=left|right|all|"..." SEQNUM=nnn SKIP=nnn DINGBAT=entity-name SRC="..." MD="..." NOWRAP>characters... </H1>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group heading
Variations: RFC 1866 recommends that a document use the header elements in order, without breaks, beginning with H1. (ed: I have not identified a browser that enforces this.) The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify Netscape 2.0 implements ALIGN=center|left|right The ID attribute was proposed in HTML+ and Version 3 to replace the NAME attribute in the A element to establish internal hyperlink destinations. With the expected use of ID for style sheets, this is likely to change. All other attributes are proposed in Version 3. RFC 1866 states typical rendering is bold, very large font, centered; when printed causes a page break. Headings are Level 0 elements.

Description: The H2 element identifies text to be separated and displayed less prominently than H1 but more prominently than H3.
Minimum Attributes: <H2>characters... </H2>
All Possible Attributes: <H2 LANG="..." DIR=ltr|rtl ID="..." CLASS="..." ALIGN=left|center|right|justify CLEAR=left|right|all|"..." SEQNUM=nnn SKIP=nnn DINGBAT=entity-name SRC="..." MD="..." NOWRAP>characters... </H2>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group heading
Variations: RFC 1866 recommends that a document use the header elements in order, without breaks, beginning with H1. (ed: I have not identified a browser that enforces this.) The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify Netscape 2.0 implements ALIGN=center|left|right The ID attribute was proposed in HTML+ and Version 3 to replace the NAME attribute in the A element to establish internal hyperlink destinations. With the expected use of ID for style sheets, this is likely to change. All other attributes are proposed in Version 3. RFC 1866 states typical rendering is bold, large font, flush left. Headings are Level 0 elements.

Description: The H3 element identifies text to be separated and displayed less prominently than H2 but more prominently than H4.
Minimum Attributes: <H3>characters... </H3>
All Possible Attributes: <H3 LANG="..." DIR=ltr|rtl ALIGN=left|center|right|justify ID="..." CLASS="..." CLEAR=left|right|all|"..." SEQNUM=nnn SKIP=nnn DINGBAT=entity-name SRC="..." MD="..." NOWRAP>characters... </H3>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group heading
Variations: RFC 1866 recommends that a document use the header elements in order, without breaks, beginning with H1. (ed: I have not identified a browser that enforces this.) The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify Netscape 2.0 implements ALIGN=center|left|right The ID attribute was proposed in HTML+ and Version 3 to replace the NAME attribute in the A element to establish internal hyperlink destinations. With the expected use of ID for style sheets, this is likely to change. All other attributes are proposed in Version 3. RFC 1866 states typical rendering is italic, large font, slightly indented. Headings are Level 0 elements.

Description: The H4 element identifies text to be separated and displayed less prominently than H3 but more prominently than H5.
Minimum Attributes: <H4>characters... </H4>
All Possible Attributes: <H4 LANG="..." DIR=ltr|rtl ALIGN=left|center|right|justify ID="..." CLASS="..." CLEAR=left|right|all|"..." SEQNUM=nnn SKIP=nnn DINGBAT=entity-name SRC="..." MD="..." NOWRAP>characters... </H4>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group heading
Variations: RFC 1866 recommends that a document use the header elements in order, without breaks, beginning with H1. (ed: I have not identified a browser that enforces this.) The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify Netscape 2.0 implements ALIGN=center|left|right The ID attribute was proposed in HTML+ and Version 3 to replace the NAME attribute in the A element to establish internal hyperlink destinations. With the expected use of ID for style sheets, this is likely to change. All other attributes are proposed in Version 3. RFC 1866 states typical rendering is bold, normal font, indented more than H3. Headings are Level 0 elements.

Description: The H5 element identifies text to be separated and displayed less prominently than H4 but more prominently than H6.
Minimum Attributes: <H5>characters... </H5>
All Possible Attributes: <H5 LANG="..." DIR=ltr|rtl ALIGN=left|center|right|justify ID="..." CLASS="..." CLEAR=left|right|all|"..." SEQNUM=nnn SKIP=nnn DINGBAT=entity-name SRC="..." MD="..." NOWRAP>characters... </H5>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group heading
Variations: RFC 1866 recommends that a document use the header elements in order, without breaks, beginning with H1. (ed: I have not identified a browser that enforces this.) The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify Netscape 2.0 implements ALIGN=center|left|right The ID attribute was proposed in HTML+ and Version 3 to replace the NAME attribute in the A element to establish internal hyperlink destinations. With the expected use of ID for style sheets, this is likely to change. All other attributes are proposed in Version 3. By default, Netscape uses a font size for H5 that is smaller than default text. For most other browsers, the font size for all headers is at least as large as the default text. RFC 1866 states typical rendering is italic, normal font, indented as H4. Headings are Level 0 elements.

Description: The H6 element identifies text to be separated and displayed less prominently than H5 but more prominently than default text.
Minimum Attributes: <H6>characters... </H6>
All Possible Attributes: <H6 LANG="..." DIR=ltr|rtl ALIGN=left|center|right|justify ID="..." CLASS="..." CLEAR=left|right|all|"..." SEQNUM=nnn SKIP=nnn DINGBAT=entity-name SRC="..." MD="..." NOWRAP>characters... </H6>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group heading
Variations: RFC 1866 recommends that a document use the header elements in order, without breaks, beginning with H1. (ed: I have not identified a browser that enforces this.) The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify Netscape 2.0 implements ALIGN=center|left|right The ID attribute was proposed in HTML+ and Version 3 to replace the NAME attribute in the A element to establish internal hyperlink destinations. With the expected use of ID for style sheets, this is likely to change. All other attributes are proposed in Version 3. By default, Netscape uses a font size for H6 that is smaller than default text. For most other browsers, the font size for all headers is at least as large as the default text. RFC 1866 states typical rendering is bold, normal font, not indented. Headings are Level 0 elements.

HEAD

Description: The HEAD contains general information about the document. None of the elements authorized to exist in the contents of the HEAD are displayed; the displayed material is found within the BODY.
Minimum Attributes
All Possible Attributes: <HEAD LANG="..." DIR=ltr|rtl> </HEAD>
Elements Allowed Within...: <TITLE><ISINDEX> <BASE> <META> <LINK> <NEXTID>
Allowed In Content Of...: <HTML>
Variations: The HTML, HEAD, and BODY elements were introduced with RFC 1866, and are currently optional, but are considered Level 0 elements. RFC 1866 recommends against permitting the NEXTID element in HEAD. The LANG and DIR attributes are introduced with the internationalization proposal. Version 3 proposes the new elements of RANGE and STYLE as allowed within a HEAD.
Sandia Requirements: The HTML, HEAD and BODY elements are required.

HPn

Description: The HP set of elements, with n=1,2,... provided a mechanism to highlight the characters in a phrase with one of a set of browser defined highlight mechanisms.
Minimum Attributes: <HPn>characters... </HPn>
All Possible Attributes: <HPn>characters... </HPn>
Variations: HPn was an early idea about highlighting but is seldom used or implemented. RFC 1866 does not include these elements, and these elements should be considered obsolete.

Description: The HR element produces a divider between sections of text.
Minimum Attributes: <HR>
All Possible Attributes: <HR DIR=ltr|rtl ALIGN=left|right|center|justify ID="..." CLASS="..." CLEAR=left|right|all|"..." SRC="..." MD="..." SIZE=number WIDTH=number|percent NOSHADE>
Elements Allowed Within...: The HR element is defined as having no content.
Allowed In Content Of...: Any element that permits members of group body.content
Variations: RFC 1866 states that the HR element is typically rendered as a full width horizontal rule or equivalent graphic. The DIR attribute is introduced with the internationalization proposal since DIR can have meaning in those cases where the horizontal rule is not full width. The internationalization proposal also includes ALIGN=center|left|right|justify The CLEAR, SRC, and MD attributes are proposed in Version 3. SRC is proposed to specify a custom image for the rule. Some browsers draw the line only within the current text margins (which may be indented on left and/or right due to lists, etc.) SIZE, WIDTH, ALIGN, and NOSHADE attributes are Netscape extensions, but Netscape 2.0 only implements ALIGN=center|left|right The HR element is Level 0.

HTML

Description: The HTML element is intended to bracket the entire HTML text in the document. All other HTML elements are inside the start and end of the HTML element.
Minimum Attributes
All Possible Attributes: <HTML VERSION="..." LANG="..." DIR=ltr|rtl> </HTML>
Elements Allowed Within...: <HEAD><BODY> <PLAINTEXT>
Allowed In Content Of...: The element HTML is the outermost element and should not be nested inside any element. RFC 1866 introduced the VERSION attribute. The LANG and DIR attributes are introduced with the internationalization proposal.
Variations: The HTML, HEAD, and BODY elements were introduced with RFC 1866, and are currently optional, but are considered Level 0 elements. RFC 1866 identifies the presence of the PLAINTEXT element within the HTML content as deprecated.
Sandia Requirements: The HTML, HEAD and BODY elements are required.

Description: The I element changes the physical rendering of the contents of the element to an italics (or slanted) font.
Minimum Attributes: <I>characters... </I>
All Possible Attributes: <I LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </I>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of group font
Variations: Browsers who do not have italics may render in some other manner. RFC 1866 states that <B> content must be rendered as distinct from <I> content. The LANG and DIR attributes are introduced with the internationalization proposal. All character definition elements are Level 2.

IMG

Description: The IMG element allows an image file to be inserted within an HTML document along with the text. The ALT attribute defines parsed character data that will be displayed if the image is not or cannot be displayed by the browser. The SRC attribute identifies a URL for retrieving the image. The ISMAP attribute is only meaningful if the IMG element is within the contents of an A element, and a responding cgi-bin program has been established at the URL identified by the HREF attribute of the A element. If a single A element spans both an image and text, the cgi-bin program will receive the HREF input values, if any, if the text is selected, or the x,y cursor pixel coordinates relative to 0,0 as the the upper-left corner of the image if the image is selected. For references to this advanced feature, see Acknowledgements.
Minimum Attributes: <IMG SRC="...">
All Possible Attributes: <IMG SRC="..." ALT="..." ISMAP LANG="..." DIR=lrt|rtl ID="..." CLASS="..." MD="..." ALIGN=bottom|middle|top|left|right|texttop|absmiddle|baseline|absbottom HEIGHT=value WIDTH=value UNITS="..." BORDER=value LOWSRC="..." HSPACE=value VSPACE=value USEMAP="..." DYNSRC="..." START=fileopen|mouseover CONTROLS LOOP=number|INFINITE|-1 LOOPDELAY=number>
Elements Allowed Within...: The IMG element is defined as having no content.
Allowed In Content Of...: Any element that permits members of group text
Variations: The attributes BORDER, HEIGHT, WIDTH, HSPACE, VSPACE, and LOWSRC are Netscape 1.1 extensions. The attributes DYNSRC, START, CONTROLS, LOOP, and LOOPDELAY are MS Internet Explorer 2.0 extensions. The LANG and DIR attributes are introduced with the internationalization proposal and relate to the value of the ALT attribute. Version 3 proposes adding the WIDTH and HEIGHT attributes. RFC 1866 defines only bottom|middle|top as values for the ALIGN attribute. The additional values for the ALIGN attribute are Netscape extensions, and include the capability to define floating images. Version 3 proposes adding only the (left|right) values for ALIGN to identify images that imply that text can float around the image. Some image capable browsers will display the ALT text until the full image is retrieved. RFC 1866 states that Level 0 conformance must accept the element, but Level 1 conformance is required before it displays the image. Version 3 proposes the UNITS attribute for use by the WIDTH and HEIGHT attributes to define units other than pixels. RFC 1866 states that an IMG element with an ISMAP element must only exist in the content of an A element with an HREF attribute. Version 3 proposes a FIG element as an advanced alternative to the IMG element, for more sophisticated multi-part overlay images, more control over text that is the equivalent of ALT, and with a proposed SHAPE attribute on the A element a method to perform the common use of the ISMAP attribute without the need for a responding cgi-bin program. The USEMAP is part of an alternate proposal for client-side image mapes. It is implemented as a Netscape 2.0 extension. USEMAP specifies a URL with a "#NAME" suffix to identify a file and MAP name, and is used with the MAP element. DYNSRC is defined by MS Internet Explorer 2.0 as the address of a video clip or VRML world to be displayed if your browser is capable, otherwise display SRC. START is defined by MS Internet Explorer 2.0 as when the videoclip or VRML world is to be displayed. If START=mouseover, the SRC image is displayed until the mouse cursor is over that image. CONTROLS is defined by MS Internet Explorer 2.0 as displaying a set of controls under the animation. LOOP is defined by MS Internet Explorer 2.0 as how many times a video clip will loop when activated. If LOOP=-1 or LOOP=INFINITE, it will loop indefinately. LOOPDELAY is defined by MS Internet Explorer 2.0 as how long, in milliseconds, a video clip will wait between replays.
Sandia Requirements: The ALT attribute and a value describing the image is required. If known, the BORDER, HEIGHT, and WIDTH attributes are recommended as they improve download performance on some browsers. If used, the HEIGHT and WIDTH attributes shall specify the actual size of the stored image in pixels.

INPUT

Description

The INPUT element is used to specify a simple input field as part of the contents in a FORM element. TYPE=text is default. NAME defines the symbolic name of the field returned to the server on submission and must be present for all but TYPE=submit|reset. For TYPE=checkbox|radio, multiple INPUT elements may have the same NAME value. TYPE=radio insures that exactly one choice amongst INPUT elements with the same NAME value is selected at all times. VALUE is used to specify a default. For TYPE=text|password VALUE defines default text to be returned, which normally is null. For TYPE=password the value should be obscured as it is entered. For TYPE=checkbox|radio VALUE defines the value returned when the checkbox or radio is selected, which defaults to "on" For TYPE=submit|reset VALUE defines the label for the pushbutton. Multiple TYPE=submit should have different NAME values to identify which submission button was selected. CHECKED defaults the specific checkbox or radio INPUT to selected. For TYPE=radio the default element checked is the first among those with the same NAME value. TYPE=image defines an image, whose URLis identified by the SRC attribute, which, when clicked, performs the form submission and sends the X,Y coordinates of the click, similar to ISMAP in the IMG element. SIZE and MAXLENGTH are only used with TYPE=text|password. SIZE is the physical size of the displayed input field expressed in characters or characters,rows. MAXLENGTH is the maximum number of characters that are accepted as input.

Minimum Attributes

<INPUT>

All Possible Attributes

<INPUT TYPE="text | password | checkbox | radio
  | submit | reset | hidden | image | file | range | scribble |
  jot" LANG="..." DIR=ltr|rtl ID="..."
  CLASS="..." NAME="..." VALUE="..."
  SRC="..." CHECKED SIZE="..." MAXLENGTH=number
  ALIGN=top|middle|bottom|left|right ACCEPT="..." DISABLED
  ERROR="..." MIN=number MAX=number MD="...">

Elements Allowed Within...

The INPUT element is defined as having no content.

Allowed In Content Of...

<FORM>

Variations

RFC 1866 defines the TYPE attribute values of text|password|checkbox|radio|submit|reset|hidden|image The <TEXTAREA> element should be used instead of this INPUT element for multiline input areas. TYPE=hidden VALUE="..." is recognized by some browsers, and is used to submit fixed information not entered by the user. Note that RFC 1866 sets a max limit of 1024 characters on VALUE. RFC 1866 only defines ALIGN=top|middle|bottom

RFC 1867 defines a mechanism for FORM-based file upload. It defines the value file for the TYPE attribute and defines a new ACCEPT attribute. Specifying TYPE=file permits attaching one or more local files to the submitted output. The browser may permit the user to specify multiple file names in response to a single INPUT element with TYPE=file ACCEPT is a list of media types or type patterns allowed for input. The valid ACCEPT values and meaning of those values is platform dependent. The value for the VALUE attribute specifies a default file name. The browser must ask for confirmation before sending any file based on the default file name. A value for the SIZE attribute of "width,height" would specify a default filename width for the input display and height sufficient to show some number of files. A value for the MAXLENGTH attribute specifies a maximum Content-Length (in bytes) which the responding server is likely to accept for transferred files. Including an INPUT element with TYPE=file requires also specifying ENCTYPE="multipart/form-data" METHOD=post on the enclosing FORM element. If the FORM does not specify this ENCTYPE, the behavior is unspecified and the file transfer is likely to be rejected by the responding server. Netscape 2.0 implements FORM-based file upload.

The LANG and DIR attributes are introduced with the internationalization proposal. Version 3 proposes the additional TYPE attribute values of range|scribble. A beta version of Netscape includes a TYPE attribute value of jot which is similar to scribble. Version 3 proposes the additional DISABLED, ERROR, MIN, MAX, and MD attributes. The Version 3 proposed TYPE=range uses the proposed MIN and MAX attributes to specify limits to numeric (real or integer) input. The proposed default value is halfway between MIN and MAX. The Version 3 proposed TYPE=scribble is to allow the user to scribble with a pointing device on top of the image specified with the SRC attribute. The Version 3 proposed DISABLED attribute would display this INPUT, but prohibit user entry/modification. The Version 3 proposed ERROR attribute defines text to be displayed in the event that the entered value for this INPUT is invalid. All elements concerning FORM are Level 2.

INS

Description: The INS element changes the character rendering of the contents of the element to logically represent inserted text, for instance in modifications in legal documents.
Minimum Attributes: <INS>characters... </INS>
All Possible Attributes: <INS LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </INS>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The INS element is a Version 3 proposed element. All character definition elements are Level 2.

ISINDEX

Description: This element appears to be a precursor to the <FORM> element which has more features. When placed in the BODY of the document, it requires the ACTION attribute to point to a cgi-bin program which can handle the query, and produces a simple INPUT field with a prompt of: "This is a searchable index. Enter search keywords:" When placed in the HEAD of the document, it informs the browser that the document is an index document and can be examined using a keyword search. The ISINDEX element is usually generated automatically by a server-side script.
Minimum Attributes: <ISINDEX>
All Possible Attributes: <ISINDEX LANG="..." DIR=ltr|rtl ACTION="..." PROMPT="...">
Elements Allowed Within...: The ISINDEX element is defined as having no content.
Allowed In Content Of...: the element <HEAD> and any element that permits members of the group block.forms
Variations: ISINDEX is a Level 0 element. The new, more sophisticated FORM element is now used more widely. The LANG and DIR attributes are introduced with the internationalization proposal. Version 3 proposes the PROMPT attribute. The PROMPT attribute is a Netscape extension.

KBD

Description: The KBD element changes the character rendering of the contents of the element to logically represent text entered as keyboard input.
Minimum Attributes: <KBD>characters... </KBD>
All Possible Attributes: <KBD LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </KBD>
Elements Allowed Within...: members of group text
Allowed In Content Of...: Any element that permits members of the group phrase
Variations: While intended to be distinguishable from CODE, so that input and output would be different, most browsers render this the same as CODE, simply as a fixed-width font. The LANG and DIR attributes are introduced with the internationalization proposal. All character definition elements are Level 2.

LANG

Description: The LANG element is used to change the default LANG context for subsequent elements from the current default. A LANG attribute on an element overrides this default LANG context for the content of that particular element.
Minimum Attributes: <LANG>characters... </LANG>
All Possible Attributes: <LANG ID="..." CLASS="...">characters... </LANG>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The LANG element is a Version 3 proposed element. All character definition elements are Level 2.

Description: The LH element defines a list header used as a title for a list. Browsers can use this in place of the full list when a mechanism is provided to fold and unfold nested lists.
Minimum Attributes: <LH>characters... </LH>
All Possible Attributes: <LH LANG="..." DIR=ltr|rtl ID="..." CLASS="...">characters... </LH>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: <DL><OL> <UL>
Variations: The LH element is proposed in Version 3 as an optional element at the beginning of some lists. It is expected that browsers may render this element in a different style/font than the list itself.

Description: The LI element defines a list item. It is rendered differently depending upon the list within which it appears.
Minimum Attributes: <LI>characters...
All Possible Attributes: <LI LANG="..." DIR=ltr|rtl ALIGN=center|left|right|justifywithin UL TYPE=disk|circle|square within OL TYPE=A|a|I|i|i within OL VALUE=n>characters...</LI>
Elements Allowed Within...: members of groups text block
Allowed In Content Of...: <DIR><MENU> <OL> <UL>
Variations: The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify The TYPE and VALUE attributes are Netscape extensions. The validity of their presence and possible values depends on the particular list entity of which this is a list item. Most browsers assume the list item ends with the beginning of the next list item or the end of the list and do not require the closing tag </LI> All list elements are Level 0.

LINK

Description

The LINK element is used to indicate a relationship between this document and other documents or objects. Multiple LINK elements may exist in a document. A LINK in document A with an HREF to document/object B with REL=relation identifies a relationship that B has to A that A recognizes/authorizes/verifies. A LINK in document B with an HREF to document/object A with REV=relation that is the identical relation identifies a desired/expected/claimed relationship of B to document/object A, but must be verified by checking with A. For further description of the LINK attributes, see the A element.

Minimum Attributes

<LINK HREF="..." >

All Possible Attributes

<LINK HREF="..." REL="..." REV="..."
  LANG="..." DIR=ltr|rtl CHARSET="..." URN="..."
  TITLE="..." METHODS="..." >

Elements Allowed Within...

The LINK element is defined as having no content.

Allowed In Content Of...

<HEAD>

Variations

The LANG, DIR and CHARSET attributes are introduced with the internationalization proposal. The CHARSET attribute is a hint as to the expected character set used by the hyperlink. Some browsers will expect a LINK REV relationship of "made" to be a "mailto:name@e-mail_address" to facilitate sending comments to the person that made the document. Contrary to the specification of the standard, this seems to only work if "made" is the only relationship in that LINK element. In addition to those mentioned with the A element, Version 3 reserves some relations for REL that are expected to be used for document specific toolbars. Currently these include

Home, ToC, Index, Glossary, Copyright, Up, Next, Previous,
  Help, Bookmark

. Version 3 also discusses relations for a document banner and style sheets. LINK is a Level 0 element.

Sandia Requirements

A LINK element in the HEAD to identify the owner of the document responsible for its accuracy is required by Sandia's automated Web tools:

<LINK REV="owns" TITLE="Full Name"
  HREF="mailto:owner-e-mail@sandia.gov">

LINK elements are also recommended to identify other individuals and their relationships to this document. The REV value of made should be used to identify the author of the document. Suggested values for REV in additional LINK elements are: approves, editor, publisher.

Large documents which are separated into smaller HTML subdocuments should use the LINK element with the REL attribute to identify these relationships. The parent document should identify all subdocuments by:
<LINK REL="Subdocument" TITLE="Subdoc Name" HREF="link-url">
The subdocument may identify its parent by:
<LINK REV="Subdocument" TITLE="Maindoc Name" HREF="link-url">
Any Sandia document which is part of a set of HTML subdocuments which form a sequence or hierarchy should include two specific LINK elements identifying the REL values of next and previous. Only one next and one previous relationship may be specified in a document.

Any of the other document relationships mentioned in this Reference Manual may also be used.

LISTING

Description: The LISTING element defined a separated multi-line set of text to be rendered as it exists in the source document with the same line breaks.
Minimum Attributes: <LISTING>characters... </LISTING>
All Possible Attributes: <LISTING WIDTH="..." >characters... </LISTING>
Elements Allowed Within...: The only markup recognized is the LISTING ending element.
Allowed In Content Of...: Any element that permits members of group block
Variations: Most browsers use fixed-width characters for LISTING text. This element existed in Version 0 and has been replaced by the <PRE> element. RFC 1866 states that the content of the LISTING element should be rendered so that at least 132 characters fit on a line. RFC 1866 has declared LISTING as deprecated and some current browsers no longer recognize it.

MAP

Description: The MAP element is used to name and describe a client-side image map. This is a set of areas defined on an image which can be selected for hyperlinks. NAME defines the map name to be used with the USEMAP attribute on an IMG element.
Minimum Attributes: <MAP NAME="..."></MAP>
All Possible Attributes: <MAP NAME="..."></MAP>
Elements Allowed Within...: <AREA>
Allowed In Content Of...: -In progress, to be determined-
Variations: The MAP element is part of a proposed enhancement to provide client-side image maps. It is implemented in Netscape 2.0.

MARQUEE

Description: The MARQUEE element defines an area in which visual scrolling will be used to display the content of the element.
Minimum Attributes: <MARQUEE>characters... </MARQUEE>
All Possible Attributes: <MARQUEE ALIGN=top|middle|bottom BEHAVIOR=scroll|slide|alternate BGCOLOR=#rrggbb|colorname DIRECTION=left|right HEIGHT=number|number% HSPACE=number LOOP=number|INFINITE|-1 SCROLLAMOUNT=number SCROLLDELAY=number VSPACE=number>characters... </MARQUEE>
Elements Allowed Within...: -In progress, to be determined-
Allowed In Content Of...: -In progress, to be determined-
Variations: The MARQUEE element is a MS Internet Explorer 2.0 enhancement. Based on the description it might be assumed that only parsed character data may be in the content of the MARQUEE element. The ALIGN attribute defines the location of the text within the marquee. The BEHAVIOR attribute determines whether the text will scroll completely in and completely off (the default), slide in and stay, or bounce between alternate sides of the marquee. The BGCOLOR attribute defines the background color for the marquee, which is specified as an "#rrggbb" number, or the following color names: Black, Maroon, Green, Olive, Navy, Purple, Teal, Gray, Silver, Red, Lime, Yellow, Blue, Fuchsia, Aqua, White. The DIRECTION attribute specifies the direction towards which the text should flow. The HEIGHT attribute specifies the height of the marquee, either in pixels or with a percentsign character suffix to define a percentage of the entire screen height. The HSPACE and VSPACE attributes are specified in pixels and define the amount to separate the marquee from surrounding text. The LOOP attribute specifies how many times the text will loop. If LOOP=-1 or LOOP=INFINITE, the text will loop indefinately. The SCROLLAMOUNT specifies the number of pixels and the SCROLLDELAY specifies the number of milliseconds between each successive draw of the marquee text.

Description: The MENU element defines an unordered list consisting of a number of separated multi-line <LI> elements which may or may not be marked by a bullet or similar symbol.
Minimum Attributes: <MENU></MENU>
All Possible Attributes: <MENU COMPACT LANG="..." DIR=ltr|rtl ALIGN=center|left|right|justify> </MENU>
Elements Allowed Within...: element <LI> but not any member of group block
Allowed In Content Of...: Any element that permits members of group list
Variations: This list type is often rendered identically to UL. RFC 1866 states that while similar to the UL element, MENU is typically rendered in a more compact manner. The COMPACT attribute of the UL element is more often used than this MENU element. The exclusion in RFC 1866 of group block within MENU implies (among other things) that MENU can contain no nested lists, nor any paragraphs even though the LI element normally would allow this. Some browsers do not enforce this exclusion. The LANG and DIR attributes are introduced with the internationalization proposal. The internationalization proposal also includes ALIGN=center|left|right|justify By adding the PLAIN attribute to eliminate the bullets to the UL element, Version 3 proposes to remove the MENU element. All list elements are Level 0.