> 1. How does IE identify itself? Is it information that the browser
> itself passes on, or do the stats/log files make an intelligent guess
> based on what kind of software it is? If the latter, is there
> not scope
> for different browsers sharing a common engine/origin to be identified
> as each other? I recall using a 'who am I' script which Identified my
> browser as Mozilla instead of IE5. How accurate is browser
> identification anyway?
Browsers may identify themselves to the server they are requesting a file from in the HTTP headers (but ISTR that it's not mandatory). IE sends stuff like this (it varies for different flavours of IE/OS, so this is just an example):
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Browsers can be configured to lie, but most aren't. This is in fact why IE identifies itself first as Mozilla, since some older sites used to lock IE out because it wasn't Netscape! But the whole issue is clouded by the various caches that may intervene between the requesting browser and your server.
>
> 2. What are the access issues surrounding 'browser sniffing'?
> Aside from
> the fact that it seems to be predominantly Javascript-based, are there
> issues arising from identifying the browser and serving up the
> content/style accordingly? And to what extent can a
> combination of XHTML
> and CSS overcome different browser requirements?
Browser sniffing is IMO pointless and unreliable. It seems to stem from an obsession with trying to achieve the pixel-perfection of colour and layout you can achieve in print publishing in the very different environment of the web. It only works if javascript is enabled; you have to keep updating it as new browsers are developed; and there are hundreds (or more) of browsers out there, so who wants to write sniffer scripts for those?
You can easily exclude older browsers from more recent CSS without resorting to it, and if it's a javascript problem you should use object detection rather than browser sniffing, since that method is reliable.
>
> 3. What is it that leads to these browser quirks? I have seen
> information relating to the Document Object Model and how it
> is handled,
I think in IE it's mostly a legacy problem of getting some things wrong earlier. Most of the old bugs seem to be fixed in IE6 standards mode. But for real ability to get CSS completely wrong, there's nothing to beat NN4.
> but I am not totally sure that I understand how these make one browser
> any better or worse, particularly in terms of accessibility. Is it
> possible to design in such a way that the presentation is
> independent of
> these quirks?
>
It depends what you mean by 'presentation'. It is impossible to get a web site looking exactly the same in different browsers on the same machine (hard enough in the same browser on different machines running the same OS). What does 'the same' mean in the context of different screen sizes, resolutions, window sizes/aspect ratios, colour depths, to say nothing of browsers and operating systems? But substantially the same in modern browsers can be achieved. IMO you just have to accept that older browsers (I'm talking IE4, NN4 or earlier) will get a basic presentation, without much (or all) of the eye candy - but they will get the content.
Regarding quirks, IE's most well-known are the fixed-size fonts bug (if font sizes are defined in pixels, users can't re-size the text); and IE5 and earlier (but not IE5.5 and IE6) getting the box model completely wrong. There's not a lot you can do about that. other than accept your pages will look slightly different in IE5 to the way the look in IE6. But IE6 reverts to 'old IE' mode unless you force it into standards mode with a full doctype (eg <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">).
So, no I don't think it's possible (or economically advisable to try) to get the presentation the same regardless of browser quirks. But you can design so that your site will be substantially the same across a range of modern browsers (which probably does approach 98% of graphical browsers), while not locking others out of your content. I do think it's possible to design to standards in such a way that you can enable access without losing the benefits of graphical design.
<disclaimer>
I am not a graphic designer, nor a professional web designer, but I suppose I should point at something I've done to show what I mean. This site was put together last Friday afternoon: <http://tour.prestongrange.org/>. I'm sure there are things that could be improved, but AFAICT it works for everyone.
</disclaimer>
Best wishes
Pete
--
Peter M Gray
Museums Officer
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