font property?
Like a watchful mother ensuring that her kids grow up right, the
HTML 4.0 standard has labeled a number of tags and attributes
"deprecated." Deprecated tags are on the way out; the deprecated
state means that you can still use them for the time being, but you need
to begin weaning yourself from them now, before they're officially declared
obsolete.
Think it won't happen? Guess again. The HTML 4.0 standard
officially declares the <listing>,
<plaintext>, and <xmp> tags
obsolete and no longer part of the standard. Their use might be
allowed by a browser, but any document containing them cannot be
labeled as HTML 4.0-compliant.
What's next? Here are the deprecated tags in HTML 4.0, doomed to be obsolete in (presumably) HTML 5.0:
| Tag | Replacement |
|---|
<applet> |
The <object> tag
|
<basefont>
<font> |
Appropriate stylesheet font properties
|
<center> |
The text-align stylesheet property
|
<dir>
<menu> |
The <ul> tag with appropriate styles applied
|
<isindex> |
Conventional forms
|
<s>
<strike>
<u> |
The text-decoration stylesheet property
|
|
Before you start getting all choked up over the loss of your
favorite tags, keep in mind that almost all attributes dealing with
visual presentation are deprecated as well. Attributes like
align, background, bgcolor,
height, size, and width are
deprecated in most usages, replaced by appropriate stylesheet
properties.
Many authors would argue that these attributes and tags are
convenient ways to accomplish common tasks, tasks that will be made
more difficult by forcing the use of other tags and style sheets. On
the other hand, consistent use of the right tags, attributes, and
styles makes your documents easier to maintain and use. Like it or
not, the gentle mothering of the HTML 4.0 standard will be keeping
you on the straight and narrow, HTML-wise.
And fret not. While the standard will someday eliminate those tags
and attributes, you can be sure it will be a long, long time before
any browser abandons them. If the standard is like your mother,
browsers are like back-alley hoods, trying to make it easy for you to
break the rules. The question is, where does your conscience lead you?
Better descriptions
A picture may be worth a thousand words, but HTML 4.0 leaves nothing
to chance. It provides a number of ways to better describe almost
every element in your document.
The alt attribute allows you to attach a description to
the <img> and <area> tags.
Some browsers make use of these attributes, displaying the
associated text when the mouse passes over the image or area.
Nongraphical browsers, like Lynx, use the text in lieu of the
image. The problem is that many authors forget to add
alt attributes to their images or area definitions.
HTML 4.0 requires that every <img> and
<area> tag have an alt attribute.
Of course, we all know that browsers will not strictly enforce this
rule, but you won't be able to declare your documents HTML
4.0-compliant if you leave alt out of the picture.
If you simply cannot fit your image and area descriptions within the
alt attribute, you can now turn to the
longdesc attribute. As its name implies, the value of
the longdesc attribute is the URL of a document
containing the long description of the object. This attribute may
be most useful when your image is worth more than a thousand words.
Another interesting new attribute is title. This
attribute lets you associate a bit of descriptive text with almost
any tag. It isn't clear how this text should be used, but browser
manufacturers will come up with something. Internet Explorer
displays an element's title when the mouse passes over, emulating
the "tool tip" help used in many Microsoft tools. Even if the
browser ignores the element titles, they make for a useful way to
store additional information about any tag right in your document.
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International support
As the Web has grown to encompass the world, HTML has grown to
include more features that support a broad range of languages and
presentation styles. HTML 4.0 is distinctly more international in
flavor, thanks in large part to the new lang and
dir attributes. Both of these attributes can be applied
to almost any HTML tag, allowing you to specify language-specific
information for an entire document or just a single word.
The value of the lang attribute is a two-character ISO language code.
This code tells the browser which language is being used for the
text within the element. Presumably, the browser will alter the
way it displays the text to match the common presentation used for
that language.
You can further refine the value used for the lang
attribute by adding a hyphen and a dialect name. For example, using
lang="en" tells the browser that you are using English,
while lang="en-us" narrows that down to U.S. English.
In most cases, you should use the lang attribute on the
<body> tag of your document to indicate the
language used for the entire document. If you have a text element
that is in a different language than the rest of your document, add the
lang attribute to the element enclosing that text.
The dir attribute specifies the direction in which the
text is rendered, and accepts values of either ltr
(left-to-right) or rtl (right-to-left). The default is
ltr.
This attribute helps those authors creating documents in languages
such as Hebrew or Chinese, ensuring that they will be rendered
correctly by the browser. As with the lang attribute,
you'll probably want to use the dir attribute with the
<body> tag, overriding this document-wide setting
for individual tags that might need to be rendered in the opposite
direction.
Editing support
Traditionally, HTML has given little support for automated document
production. Early versions of HTML included the
<nextid> tag to create unique sequence numbers
within a document, but few, if any editing tools used the tag.
Until HTML 4.0, no tags existed to support the process of document
creation and editing.
Within HTML 4.0 you'll find two new tags: <ins>
and <del>. They can be used in almost any
context within a document to delimit a region of markup that has been
either inserted into or deleted from that document. A
conforming browser would use the tags to display the document in an
appropriate manner. If, for example, a user wanted to see the end result
of his or her edits, the inserted text would be displayed and the deleted text
removed. If an editor wanted to see the changes made to a
document, the deleted text might be displayed with a line struck
through it.
Both of these tags accept two attributes: cite and
datetime. The cite attribute supplies the
URL of a document explaining why the associated edit was made, and
might include other information like the author's name. The
datetime attribute indicates the time at which the edit
was made. Using these timestamps, a browser might even be able to
re-create a version of a document as it existed at a specific point
in time.
Link targets everywhere
From its earliest versions, HTML has supported what is sometimes
called a fragment identifier: a label associated with the
<a> tag that allows a URL to jump to a specific
spot within a document. Thus, you might place
<h2><a name="section1">Section 1</a></h2>
in your document, and jump to that spot from another document using
<a href="document.html#section1">
This is a great idea, but is sometimes tedious to implement, given
all the extra <a> tags it requires.
HTML 4.0 makes the creation of fragment identifiers much easier by
adding the id attribute to just about every tag in the
standard. This attribute defines a name, just like the
name attribute that can be referenced by a URL
pointing to the document. To re-create our example in HTML 4.0, you
would enter:
<h2 id="section1">Section 1</h2>
With the ability to name any HTML element, automated tools can more
easily extract sections of documents for later processing. For
example, by naming the paragraphs containing your documents'
abstracts with id="abstract", you can quickly find all
your abstracts. In addition, the names created with the
id attribute can be used to create style classes that
can be applied to the tag independent of normal HTML styles. Thus,
if you have two style rules like these
.blue { color : blue }
#bold { font-weight : bold }
You could create a bold, blue paragraph with
<p class=blue id=bold>
Since the value of the id attribute must be unique
throughout the document, only one tag within the document can be
given the #bold style.
More sensitive elements
With the development of JavaScript, HTML 3.2 added a few event
handlers to certain tags. Netscape and Internet Explorer went
further, making many tags sensitive to various input events like
mouse motion and keypresses. HTML 4.0 standardizes the kinds of
events that almost any element can respond to with a set of element
event handlers.
The events recognized by HTML 4.0 are:
| Attribute | Event |
|---|
<onclick> |
Any mouse button was clicked
|
<ondblclick> |
Any mouse button was double-clicked
|
<onkeydown> |
A key was pressed down
|
<onkeypress> |
A key was pressed and released
|
<onkeyup> |
A key was released
|
<onmousedown> |
A mouse button was pressed down
|
<onmousemove> |
The mouse moved within the element
|
<onmouseout> |
The mouse moved out of the element
|
<onmouseover> |
The mouse moved into an element
|
<onmouseup> |
A mouse button was released
|
|
Some of these attributes correspond to older, nonstandard
attributes. For example, onmouseover and
onmouseout correspond to the onfocus and
onblur attributes.
For all of these attributes, the value is a bit of executable
script, usually JavaScript. You might invoke a JavaScript routine
defined elsewhere in the document, or you might stick a single
statement or two directly into the attribute value. Either way,
these attributes give you a consistent way to associate dynamic
activity with any element in your document.
Moving ahead
As I noted when we started, you can't really test most of these new
features, as they won't be supported until the next release of
Netscape and Internet Explorer. Until that happens, you may want to
start thinking about how you'll need to change your documents to
conform to the new standard. More importantly, start thinking about
using these new features to make your documents easier to use, more
inviting, and easier to maintain.
Resources
About the author
Chuck Musciano has been running various Web sites, including the
HTML Guru Home Page,
since early 1994, serving up HTML tips and tricks to hundreds of
thousands of visitors each month. He's been a beta tester and
contributor to the
NCSA httpd project
and speaks regularly on the Internet, World Wide Web, and related topics.
Chuck is currently CIO at the American Kennel Club.
Reach Chuck at chuck.musciano@sunworld.com.
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e're
wrapping up our tour through HTML 4.0 this month. In
April we went through all the new table features, in
May we followed up with all the new forms features, and this month we'll close out with a look at a number of small, but important, additions to HTML in the 4.0 standard.
