I was under the impression that WWW was deprecated but a lot of the sitemap generators seem to rather i use it. I know that Google doesn't like if i mix the two, IE if the URL of the sitemap is
http://domain.com/sitemap.xml and the internal links show WWW. etc. Can anyone enlighten me.
Edit: Thanks for all the answers but I think I haven't been specific enough in the question, sorry; what I was trying to find out was why it seemed that the sitemap generators wanted me to put the WWW version in.... I discovered from reading Dan Diplo 's answer below that I was making a mistake in thinking that I could simply choose at the sitemap generator stage which was the canonical version - in my case anyway this had already been chosen (by me) at my server level and typing the other version into the generators was causing strange results. Thanks for the other informative answers too.