Why do some URLs for a specific client have "/index.shtml"?

[FranFerrara]

Reviewing our client's URLs for a 301 redirect strategy, we have noticed that many URLs have "/index.shtml." The part we don'd understand is these URLs aren't the homepage and they have multiple folders followed by "/index.shtml" Does anyone happen to know why this may be occurring? Is there any SEO value in keeping the "/index.shtml" in the URL?

[customerparadigm.com]

SHTML is an old-school way to use SSI (server side includes) in what is otherwise a static HTML page.
Stack Overflow talks about this in more detail here:
http://stackoverflow.com/questions/519619/what-is-shtml

Web servers know that if the page is .shtml, then it's okay to run inline php code, for example.

My guess is that your .shtml files are older remnants of SSI files.

I'm not a big fan of changing URLs just to clean up things, because if you change links you will need to use a 301 redirect, and that will keep about 85% of the SEO value of the original link.

If you do want to use inline php code on .html pages, I agree with Travis, above. You can modify your .htaccess file with:

addhandler x-httpd-php5-cgi .htm
addhandler x-httpd-php5-cgi .html

(This will allow you to run php in static HTML files, without having to change the file extension to .php)

Hope this helps!

• Jeff

[Travis_Bailey]

It sounds like there's a problem with the .htaccess file. There's a lot of potential negatives to the situation. One of those is duplicate content.

Find out if the potential duplicates are indexed. Perform a link audit for those pages and 301 or 410, depending upon value. I'm not a big fan of 'excessive' 301 redirects, so knowing nothing else about the situation I would err on the side of 410s.