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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML lang=en><HEAD><TITLE>4 Reasons to Validate your HTML</TITLE>
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<H1>4 Reasons to Validate your <ABBR class=initialism
title="HyperText Markup Language">HTML</ABBR></H1>
<P><ABBR class=initialism title="HyperText Markup Language">HTML</ABBR>
validation allows authors to check their <ABBR class=initialism
title="HyperText Markup Language">HTML</ABBR> syntax. Valid <ABBR
class=initialism title="HyperText Markup Language">HTML</ABBR> is less likely to
cause problems with different browsers and more likely to survive the next
browser release. There are many reasons to validate your <ABBR class=initialism
title="HyperText Markup Language">HTML</ABBR>, but here we have chosen to focus
on just 4 reasons that show why visually checking your Web pages in browsers is
not enough.</P>
<H2>Reason #1: Netscape 1.2</H2>
<P>When Netscape 1.1 was released, many authors were delighted to find that they
could create animated titles and backgrounds by including multiple <STRONG
class=html><TITLE></STRONG> and <STRONG class=html><BODY></STRONG>
tags. Validators flagged these as errors since only one <STRONG
class=html>TITLE</STRONG> and <STRONG class=html>BODY</STRONG> is permitted in
<ABBR class=initialism title="HyperText Markup Language">HTML</ABBR>.</P>
<P>Netscape 1.2 fixed the bug in Netscape 1.1, and multiple <STRONG
class=html><TITLE></STRONG> and <STRONG class=html><BODY></STRONG>
tags were ignored. The result on some invalid pages varied from an incomplete or
incoherent title to unreadable text.</P>
<H2>Reason #2: Netscape 2.0</H2>
<P>Netscape 2.0 provided the most stark display of the importance of validation.
Prior to Netscape 2.0, the Web's most popular browser quietly corrected an
author's missing quotation mark, as in <STRONG class=html><A
HREF="oops.html>Oops</A></STRONG>. Netscape 2.0 began requiring that
closing quotation mark, and at the same time parts of many Web pages began
disappearing. Valid <ABBR class=initialism
title="HyperText Markup Language">HTML</ABBR> survived unscathed.</P>
<H2>Reason #3: Netscape 3.0</H2>
<P>Netscape 3.0 began looking too hard for entities in attribute values. The
result was that unescaped ampersands in attribute values could result in
Netscape using the wrong attribute value. For example, the invalid <ABBR
class=initialism title="HyperText Markup Language">HTML</ABBR> <STRONG
class=html><A HREF="foo.pl?chapter=1&section=2"></STRONG> worked fine
in versions of Netscape prior to 3.0. But Netscape 3.0 would try to fetch
"foo.pl?chapter=1ion=2" instead of the "right" location. The valid <ABBR
class=initialism title="HyperText Markup Language">HTML</ABBR>, <STRONG
class=html><A HREF="foo.pl?chapter=1&amp;section=2"></STRONG>, has
worked fine in all versions of Netscape.</P>
<H2>Reason #4: Netscape 4.0</H2>
<P>Netscape 4.0 began requiring the terminating semicolon on entities where
previous versions often had not. For example, some <ABBR class=initialism
title="HyperText Markup Language">HTML</ABBR> tutorials show their expertise
with <STRONG class=html>&ltP&gtFoo</STRONG> in examples, which Netscape
4.0 shows literally while previous versions had shown "<P>Foo". Again,
valid <ABBR class=initialism title="HyperText Markup Language">HTML</ABBR>
worked fine in all versions of Netscape.</P>
<DIV class=footer>
<P class=toolbar><A href="/wdg-html-validator/">Validate by
<ABBR class=initialism title="Uniform Resource Locator">URL</ABBR></A> ~ <A
href="/wdg-html-validator/upload.html">Validate by file
upload</A> ~ <A href="/wdg-html-validator/direct.html">Validate by direct
input</A></P>
<DIV class=footer>
<ADDRESS>Developed and maintained by <A href="http://htmlhelp.com/~liam/">Liam
Quinn</A> <<A
href="mailto:liam@htmlhelp.com">liam@htmlhelp.com</A>></ADDRESS>
<ADDRESS>Debian Package maintained by Jaldhar H. Vyas <<A
href="mailto:jaldhar@debian.org">jaldhar@debian.org</A>></ADDRESS>
<P class=toolbar><A href="http://htmlhelp.com/"><IMG alt="Web Design Group ~ "
height=40 src="/wdg-html-validator/wdglogo-small.gif" width=105></A><A
href="/doc/wdg-html-reference/html40/">HTML 4.0 Reference</A> ~
<A href="/doc/wdg-html-reference/wilbur/">HTML 3.2 Reference</A> ~
<A href="/doc/wdg-html-reference/css/">Cascading Style Sheets Reference</A></P>
<P class=copyright><A href="http://htmlhelp.com/copyright.html">Copyright </A>
1998-99 Liam Quinn. All rights reserved.</P></DIV></DIV>
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