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EXTENSIONS TO HTML
This document explains the extensions to the HTML 2.0 specification. We're
currently working on a document about extensions to HTML 3.0 (keep your eyes
peeled to these pages); in the meantime, you can get information about
adding tables, backgrounds, and dynamic updating to documents - three
important extensions in Netscape Navigator 1.1b1 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.
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ADDITIONS
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.
The SIZE tag lets the author give an indication of how thick they
wish the horizontal rule to be.
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.
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.
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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.
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 horrible 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.
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.
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.
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.
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NEW ELEMENTS
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.
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 because using
breaks
many existing browsers when the
tag is used as a container. The
tag is also less general and does not support all cases
where centering may be desired.
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BEHAVIORAL CHANGES
Font attributes are now properly cumulative. Text inside something like
Text here
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:
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 Anchor here. broken between
the highlighted anchor and the period.
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NEW ENTITIES
In addition to the usual & escaped entities:
® -> Registered Trademark -> ¨
© -> Copyright -> ©
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