This document explains the extensions to the HTML 2.0 specification. We're currently working on a document about extensions to HTML 3.0; in the meantime, you can get information about adding tables, backgrounds, and dynamic updating to documents - three important extensions in Netscape Navigator 1.1 and beyond that are being proposed for inclusion in HTML 3.0.

Netscape Communications will continue to work with the appropriate standards bodies, including W3C and the authors of other WWW browsers, in an attempt to have these extensions available in all browsers in the near future. All of the Netscape Navigator extensions to HTML take the form of additional tags and attributes added to the HTML specification and are specifically designed not to break existing WWW browsers.


To the ISINDEX element we have added the PROMPT tag. ISINDEX indicates that a document is a searchable index. PROMPT has been added so the document author can specify what message they want to appear before the text input field of the index. The default is of course that unfortunate message:
This is a searchable index. Enter search keywords:
The HR element specifies that a horizontal rule of some sort (The default being a shaded engraved line) be drawn across the page. To this element we have added 4 new tags to allow the document author some ability to describe how the horizontal rule should look.
<HR SIZE=number>
The SIZE tag lets the author give an indication of how thick they wish the horizontal rule to be.
<HR WIDTH=number|percent>
The default horizontal rule is always as wide as the page. With the WIDTH tag, the author can specify an exact width in pixels, or a relative width measured in percent of document width.
<HR ALIGN=left|right|center>
Now that horizontal rules do not have to be the width of the page we need to allow the author to specify whether they should be pushed up against the left margin, the right margin, or centered in the page.
Finally, for those times when you really want a solid bar, the NOSHADE tag lets you specify that you do not want any fancy shading of your horizontal rule.
Your basic bulleted list has a default progression of bullet types that changes as you move through indented levels. From a solid disc, to a circle to a square. We have added a TYPE tag to the UL element so no matter what your indent level you can specify whether you want a TYPE=disc, TYPE=circle, or TYPE=square as your bullet.
Your average ordered list counts 1, 2, 3, ... etc. We have also added the TYPE tag to this element to allow authors to specify whether the want their list items marked with: capital letters (TYPE=A), small letters (TYPE=a), large roman numerals (TYPE=I), small roman numerals (TYPE=i), or the default numbers (TYPE=1).

For lists that wish to start at values other than 1 we have the new tag START. START is always specified in the default numbers, and will be converted based on TYPE before display. Thus START=5 would display either an 'E', 'e', 'V', 'v', or '5' based on the TYPE tag.

To give even more flexibility to lists, we thought it would be nice if the author could change the list type, and for ordered lists the list count index as they progressed. To this end we added the TYPE tag to the LI element as well. It takes the same values as either UL or OL depending on the type of list you are in, and it changes the list type for that item, and all subsequent items. For ordered lists we have also added the VALUE element so you can change the count, for that list item and all subsequent.
The IMG tag is probably the most extended tag.
<IMG ALIGN=left|right|top|texttop|middle|absmiddle|baseline|bottom|absbottom>
The additions to your ALIGN options needs a lot of explanation. First, the values "left" and "right". Images with those alignments are an entirely new floating image type. A ALIGN=left image will float down and over to the left margin (into the next available space there), and subsequent text will wrap around the right hand side of that image. Likewise for ALIGN=right the image aligns with the right margin, and the text wraps around the left.

The rest of the align options are my way of trying to correct for the errors I made when first implementing the IMG tag, without destroying the look of existing documents. ALIGN=top does just what it always did, which is align itself with the top of the tallest item in the line. ALIGN=texttop does what many people thought top should do which is align itself with the top of the tallest text in the line (this is usually but not always the same as ALIGN=top). ALIGN=middle does just what it always did, it aligns the baseline of the current line with the middle of the image. ALIGN=absmiddle does what middle should have done which is align the middle of the current line with the middle of the image. ALIGN=baseline aligns the bottom of the image with the baseline of the current line. ALIGN=bottom does just what it always did (which is identical to ALIGN=baseline but baseline is a better name). ALIGN=absbottom does what bottom should have done which is align the bottom of the image with the bottom of the current line.

<IMG WIDTH=value HEIGHT=value>
The WIDTH and HEIGHT tags were added to IMG mainly to speed up display of the document. If the author specifies these, the viewer of their document will not have to wait for the image to be loaded over the network and its size calculated.
<IMG BORDER=value>
This lets the document author control the thickness of the border around an image displayed. Warning: setting BORDER=0 on images that are also part of anchors may confuse your users as they are used to a colored border indicating an image is an anchor.
<IMG VSPACE=value HSPACE=value>
For the floating images it is likely that the author does not want them pressing up against the text wrapped around the image. VSPACE controls the vertical space above and below the image, while HSPACE controls the horizontal space to the left and right of the image.
With the addition of floating images, we needed to expand the BR tag. Normal BR still just inserts a line break. We have added a CLEAR tag to BR, so CLEAR=left will break the line, and move vertically down until you have a clear left margin (no floating images). CLEAR=right does the same for the right margin, and CLEAR=all moves down until both margins are clear of images.


The NOBR element stands for NO BReak. This means all the text between the start and end of the NOBR elements cannot have line breaks inserted between them. While NOBR is essential for those odd character sequences you really don't want broken, please be careful; long text strings inside of NOBR elements can look rather odd.
The WBR element stands for Word BReak. This is for the very rare case when you have a NOBR section and you know exactly where you want it to break. Also, any time you want to give the Netscape Navigator help by telling it where a word is allowed to be broken. The WBR element does not force a line break (BR does that) it simply lets the Netscape Navigator know where a line break is allowed to be inserted if needed.
<FONT SIZE=value>
Surprise! You can change the FONT size. Valid values range from 1-7. The default FONT size is 3. The value given to size can optionally have a '+' or '-' character in front of it to specify that it is relative the the document baseFONT. The default baseFONT is 3, and can be changed with the BASEFONT element.
This changes the size of the BASEFONT that all relative FONT changes are based on. It defaults to 3, and has a valid range of 1-7.
You aren't dreaming, yes you can center your text. All lines of text between the begin and end of CENTER are centered between the current left and right margins. A new tag has been introduced rather than using the proposed <P Align="center"> because using <P Align="center"> breaks many existing browsers when the <P> tag is used as a container. The <P Align="center"> tag is also less general and does not support all cases where centering may be desired.


Font attributes are now properly cumulative. Text inside something like
<i><tt><FONT SIZE=6><b>Text here</b></FONT></tt></i>
will be italic fixed bold text of size 6.

The Netscape Navigator should now properly deal with the awful HTML comment sequence. This should be:

<!-- Comment here -->
These comments can include other elements, and thus be used to quickly comment out large chunks of markup.

Line breaking is a little more under control now. Unless specified with a formatting element, lines can only be broken where empty space occurs in the original document. This means any spaces, tabs, or newlines. You should never again have the sequence <A HREF=url>Anchor here</A>. broken between the highlighted anchor and the period.


In addition to the usual & escaped entities:
&reg; -> Registered Trademark -> ®
&copy; -> Copyright -> ©

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