Why is here no wc3 validation error?

Knut Krueger · Jun 2, 2007

Hi all,
why is the code reported as valid?
IE and Opera will display nothing without the > after the link

Regards Knut

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta content="text/html; charset=windows-1252" http-equiv="content-type" >

<title>image problem</title>
</head>
<body>
<div>
<A HREF="http://www.w3.org" <img
src="http://www.w3.org/Icons/WWW/w3c_home_nb" alt="wc3"/> </A>
</div>

</body>
</html>

John · Jun 2, 2007

Knut Krueger said:
Hi all,
why is the code reported as valid?
IE and Opera will display nothing without the > after the link

Regards Knut

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>

<title>image problem</title>
</head>
<body>
<div>
<A HREF="http://www.w3.org" <img
src="http://www.w3.org/Icons/WWW/w3c_home_nb" alt="wc3"/> </A>
</div>

</body>
</html>

Why the forward slash after ("wc3") I'm no expert but that just doesn't look
right to me. I'm only guessing here until someone comes along that may be of
more help to you.

John Hosking · Jun 2, 2007

Knut said:
Hi all,
why is the code reported as valid?
IE and Opera will display nothing without the > after the link

I don't know. Maybe Jukka or Ben or somebody experienced in reading DTDs
can explain why it's allowed.

I pasted your code into the "Validate by Direct Input" box at
http://validator.w3.org/ and found that the code is indeed deemed to be
valid. Also valid is this simpler variant:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>More of a Parse Question</title>
</head>
<body>
<p>
<A </A>
</p>
</body>
</html>

I can only guess that this is an instance of one of those little-known
auto-terminating tags (although it doesn't seem to be a proper "null end
tag") that seem to work because they are rooted in SGML, but which
nobody (like, say, browser developers) knows about.

Sorry I can't be of more help. I'm interested in knowing the answer, too.

Benjamin Niemann · Jun 2, 2007

Hello,

Knut said:
why is the code reported as valid?
IE and Opera will display nothing without the > after the link

Regards Knut

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>

<title>image problem</title>
</head>
<body>
<div>
<A HREF="http://www.w3.org" <img
src="http://www.w3.org/Icons/WWW/w3c_home_nb" alt="wc3"/> </A>
</div>

</body>
</html>

The '<A ... ' followed by '<img ...' is a so-called 'unclosed start-tag'
[1], which is valid SGML syntax, but not supported by 'tag-soup' parsers
found in browsers.
There's also a XMLish '<img .. />' tag in there, which is valid in this
context, but - when parser by the SGML rules - not what you want, though
probably treat the '/' as a syntax error which is silently ignored.

Reporting such things is beyond the scope of a markup validator, though it
may be of great help for web authors.

HTH

[1]: If the start-tag is immediately followed by a TAGO '<' or STAGO '</',
you may omit the TAGC '>'.

Harlan Messinger · Jun 2, 2007

Knut said:
Hi all,
why is the code reported as valid?
IE and Opera will display nothing without the > after the link

Regards Knut

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta content="text/html; charset=windows-1252" http-equiv="content-type" >

<title>image problem</title>
</head>
<body>
<div>
<A HREF="http://www.w3.org" <img
src="http://www.w3.org/Icons/WWW/w3c_home_nb" alt="wc3"/> </A>
</div>

</body>
</html>

http://www.is-thought.co.uk/book/sgml-9.htm#Unclosed

dorayme · Jun 2, 2007

Benjamin Niemann said:
Hello,

Knut said:

why is the code reported as valid?
IE and Opera will display nothing without the > after the link

Regards Knut

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>

<title>image problem</title>
</head>
<body>
<div>
<A HREF="http://www.w3.org" <img
src="http://www.w3.org/Icons/WWW/w3c_home_nb" alt="wc3"/> </A>
</div>

</body>
</html>

Click to expand...

The '<A ... ' followed by '<img ...' is a so-called 'unclosed start-tag'
[1], which is valid SGML syntax, but not supported by 'tag-soup' parsers
found in browsers.
There's also a XMLish '<img .. />' tag in there, which is valid in this
context, but - when parser by the SGML rules - not what you want, though
probably treat the '/' as a syntax error which is silently ignored.

Reporting such things is beyond the scope of a markup validator, though it
may be of great help for web authors.

BBedit text editor reports

Unencoded entity found; "<" needs to be encoded as "<".

Document type doesn't permit empty XML element; "<img/>".

Close element "</a>" found but element wasn't open.

The iCab browser, which refuses to show anything on the page at
all, reports:

HTML error (12/57): The attribute "<IMG" in tag <A> is not
allowed.
HTML error (12/57): The attribute "SRC" in tag <A> is not allowed.
HTML error (12/57): The attribute "ALT" in tag <A> is not allowed.
HTML error (12/57): Illegal character "/" in tag.

Opera refuses too.

Safari happily displays the logo, so too does the innocent and
good old Mac IE 5

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Why is here no wc3 validation error?

Knut Krueger

John

John Hosking

Benjamin Niemann

Harlan Messinger

dorayme

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