just to elaborate on wullie's response
Not all servers are setup the same, index.htm is not always the first page the server will look for and there could be any amount of default pages that the server looks for.
as long as the file is in the list it doesn't have to be first. say for example the host's priority list is "intex.html, index.htm, index.asp, index,php, default.html, default.htm, default.asp, default.php"
if you use default.html it will show up just fine.
now if you have your real info in default.htm but somehow an index.html page gets put on the server the unwanted index.html page will be displayed. not the desired default.htm.
on another note that list is per site so you could ask your host to include main.html to the list for your site and not effect anyone else. that would give you your "
functionality without having to change the site to look at index or default and you don't have to tell your users to update or redirect.
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