Validation... why?

PicoDeath · #1 (**permalink**) Nov 20th, 2007, 20:12

I have an Assignment which needs to be handed in tomorrow, I just want to make sure of some things.

What is a doctype and why do we need to declare one within our xhtml file?
We have this cause it's a standard right? It also cuts down on cross browser errors?

Explain the meaning of xmlns and where it would be placed in an xhtml file?
I've never understood what this is and why it's used? Cause anyone elaborate?

Give a written example of xmlns
Yeah if you could.

Aso · #2 (**permalink**) Nov 20th, 2007, 20:37

Essentially, a a correct doctype will ensure a browser to render in standards mode. Without a doctype (or with an invalid one) browsers will resort to quirks mode, which can lead to spurious and unpredictable rendering of your site

Doctype's are also required for valid markup. Read more at A List Apart

Quoting on the topic of xmlns

Quote:

xmlns stands for "XML namespace". A namespace is a unique identifier for a variant of XML. It is a method to avoid conflicts with different XML variants which use the same element names.

There's a bit of discussion surrounding this, as xmlns accompanies XHTML, not HTML. XHTML was a new introduction to help integrate HTML and XML. It was not a 'new' HTML as such, and many argue XHTML should only be used for the purpose it was built for, and not simply served as 'text/html.' Read the discussion

An example of an xmlns declaration:

HTML: Select all

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

PicoDeath · #3 (**permalink**) Nov 20th, 2007, 21:05

I've done all the Assignment now apart from this one;

Explain the meaning of xmlns and where it would be placed in an xhtml file?

It's supposed to be below the DOC type if I'm correct. However, I'm lost on what the answer or general answer for the meaning/use of XMLS is? What is it supposed to do?

Oh and something called MIME which is a file extension from what I've been reading. 'A method of encoding a file for delivery over the Internet.' Does anyone know of a site which is more detailed than this description?

Thanks for your information aso so far

MikeHopley · #4 (**permalink**) Nov 21st, 2007, 08:55

Quote:

Oh and something called MIME which is a file extension from what I've been reading. 'A method of encoding a file for delivery over the Internet.'

The MIME type choice says to the browser, "this is the type of content you're getting".

XHTML should be sent with a MIME type of "application/xhtml+xml". You give the browser XHTML, and at the same time you say, "yes, this really is XHTML".

Internet Explorer does not understand XHTML at all, however. For this reason, XHTML is often sent with a MIME type of "text/html". This is somewhat like a Jedi mind trick:

Internet Explorer: "Halt! This looks suspiciously like XHTML. I will be forced to render a document parse tree instead of a webpage."

Jedi webmaster: "This is not XHTML. This is invalid HTML."

Internet Explorer: "This is not XHTML. It is invalid HTML."

Jedi webmaster: "I will render this as a normal webpage. It is tasty tag soup."

Internet Explorer: "I will render it as a normal webpage. I like tag soup."

PicoDeath · #5 (**permalink**) Nov 21st, 2007, 09:18

I might use that example actually, I'll add a little more serious-ness to it

Thanks hopley! That's helped a lot

Stuart · #6 (**permalink**) Nov 24th, 2007, 01:37

Quote:

Originally Posted by PicoDeath

I'll add a little more serious-ness to it

What do you mean? Silliness makes it more fun and better to learn from

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Validation... why?