Re: Problems with Validation

by Andrew McFarland <aamcf(at)aamcf.co.uk>

Date:	Sun, 15 Sep 2002 20:52:07 +0100
To:	<hwg-basics(at)hwg.org>
Cc:	"Caryl A. Milton" <tippybird(at)earthlink.net>
In-Reply-To:	home
	todo: View Thread, Original

At 15:06 15/09/02 -0400, Caryl Milton wrote:
>   ... cal.com/cat_disp.asp?SUB_CAT_NBR=0&CAT_NBR=7&NAV=6">
>                                          ^Error: unknown entity "CAT_NBR"

Try

SUB_CAT_NBR=0&CAT_NBR=7&amp;NAV=6

>I have tried doing a double ampersand sign in each place, but that causes an
>error message when you try to click on and visit that site.

When an & appears in an XHTML document, it indicates the start of an 
entity. If you don't mean it to be an entity, you must escape it as &amp;.

Every time you have a `&' in an (X)HTML document you must escape it with 
&amp;, even if it is in an attribute value.[1] Browsers are very lax about 
interpreting this correctly, so you almost never encounter this problem in 
real life, but you do encounter it when validating.

As an alternative, it is valid to use ; as a separator in a URL instead of 
the `&'.

SUB_CAT_NBR=0&CAT_NBR=7;NAV=6

This avoids the problem, and any well written CGI script should cope with it.

Andrew

--
http://aamcf.co.uk/

[1] Well, not quite _every_ time - but this is basics, so I won't go into 
details. It never harms to escape an `&' when you mean it to be a literal 
`&' though.

HTML: hwg-basics mailing list archives, maintained by Webmasters @ IWA