Hostile17 wrote:
[color=blue]
> Consider the following HTML.
>
> ----------
>
> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
> "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd">
> <html>
> <head>
> <meta http-equiv=Content-Type content="text/html; charset=iso-8859-1">
> <title>Untitled</title>
> <link rel="Stylesheet" href="mystylesheet.css" />
> </head><body>
> <img src="myimage.gif" alt="my image" width="100" height="100" />
> </body>
> </html>
>
> ----------
>
> There's a guy a work who insists on coding like this. Or rather,
> *some* of his images have a trailing slash, not others, and his link
> tags, as above, have them, but not his meta-tags.[/color]
It sounds like cargo-cult behaviour. Can he explain why he does it?
[color=blue]
> I don't know where he picked up the habit, but he says it's valid 4.01
> Transitional, and it's also "best practice".[/color]
The example you gave is invalid, but the practice of XML-style empty
elements _may_ result in a valid document, although only by coincidence,
and it will not mean what he thinks it means. If he's concerned with "best
practice", then he should be far more worried about using the Transitional
document type.
The real problem, though, is that he's shifted the burden of proof onto you,
when it's _him_ that needs to justify his position (as you can clearly
demonstrate error messages, even if you don't understand them).
[snip][color=blue]
> In an attempt to get an official answer on this, I validate the above
> at the W3C.
>
> I get this result:[/color]
[snip errors][color=blue]
> If I validate it with BBEdit's built-in Check Syntax, it give me this:[/color]
[snip][color=blue]
> When I show these results to the coder, he says the W3C is complaining
> about "HEAD and BODY tags on the same line" which is laughable,[/color]
He has completely misunderstood the error message. Apart from anything
else, it's trivial to prove him wrong by simply putting them on separate
lines.
[color=blue]
> but he's got a point when he says "BBEdit says the tags are empty. They're
> not empty."[/color]
BBEdit says that it doesn't permit empty XML elements. You are mixing up
tags and elements. <img> elements, for example, are always empty, although
the tags are not. Empty elements have no content, although they usually
have attributes.
[color=blue]
> I could go on trying other validators, but I'm not happy with the
> results of these.[/color]
They are working properly. Let's walk through the code:
[color=blue]
> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
> "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd">[/color]
This is an HTML 4.01 Transitional document.
[color=blue]
> <html>[/color]
Open the <html> element.
[color=blue]
> <head>[/color]
Open the <head> element, which is within the <html> element.
[color=blue]
> <meta http-equiv=Content-Type content="text/html; charset=iso-8859-1">[/color]
Opens and closes a <meta> element, which is within the <head> element. This
is an empty element.
[color=blue]
> <title>Untitled</title>[/color]
Opens the <title> element, within the <head> element, which contains the
character data 'Untitled', and closes it.
[color=blue]
> <link rel="Stylesheet" href="mystylesheet.css" />[/color]
Opens a <link> element. This is where the problem lies. An obscure part of
HTML allows authors to use shorthand syntax to write elements. For
example, the following are equivalent:
<em>...</em>
<em/.../
No browser (that I know of) implements this part of HTML, only the
validator, which is why you haven't heard of it. So, going back to the
code:
[color=blue]
> <link rel="Stylesheet" href="mystylesheet.css" />[/color]
This is actually equivalent to:
<link rel="Stylesheet" href="mystylesheet.css" >/
Now, <link> elements are always empty. So, upon encountering the solidus
(slash), the parser jumps back out one layer, to the <head> element. The
<head> element cannot contain character data, so the parser jumps out
another level (the closing tag for the <head> element is optional), to the
<html> element. The <html> element cannot contain character data either,
_but_, another little-known corner of HTML states that the <body> element
can be implied; that is to say you don't need to explicitly start it with
an opening tag. So, going back to the code (again):
[color=blue]
> <link rel="Stylesheet" href="mystylesheet.css" />[/color]
This opens a <link> element, which is empty, closes the <head> element and
starts the <body> element, which contains a solidus character.
[color=blue]
> </head><body>[/color]
Obviously, at this point, there is no <head> element to close, and you can
only have one <body> element per document, which is already open at this
point. This is the error.
[snip][color=blue]
> Validated as 4.01 Strict, by the way, these tags are definitely
> errors. "Character Data Is Not Allowed Here" with an arrow pointing to
> the end of the tag.[/color]
This is actually a different error. HTML 4.01 Strict documents do not allow
character data within <body> elements, they need to be contained within
another element, such as a <p> element. The following is not valid HTML
4.01 Strict:
....
<body>
Britney
The following is valid HTML 4.01 Strict:
....
<body>
<p>
Britney
[color=blue]
> What I want is someone to give me a definitive response, backed up by
> a link to a reputable website, where it gives an answer either way.[/color]
[snip]
The only definitive source is the specification, unfortunately it isn't
trivial to point to a single part to say "this is wrong".
<URL:http://www.w3.org/TR/html401/>
However, if you can make do with a less definitive, but pretty clear
statement from the validator guys, have a look at the validator FAQ:
<URL:http://validator.w3.org/docs/help.html#faq-linkandmeta>
--
Jim Dabell
