Is there a way to fake a .htm extension at the end of every URL on my site?

[yeehawjared]

I'm building a site similar to www.ultimate-guitar.com.  Let's digest a sample URL from their site:

http://www.ultimate-guitar.com/tabs/[color=green]l[/color]/[color=blue]led_zeppelin[/color]/[color=red]stairway_to_heaven[/color][color=orange]_ver4_[/color][color=teal]tab[/color][b].htm[/b]

I can assume the variables getting passed are something like:
[color=green]?artistLetter=l[/color]
[color=blue]?artist=led_zeppelin[/color]
[color=red]?title=stairway_to_heaven[/color]
[color=orange]?version=_ver4[/color]
[color=teal]?type=_tab[/color]
[b].htm[/b]

I can emulate this via mod_rewrite up to the point where they have "[color=red]stairway_to_heaven[/color][color=orange]_ver4_[/color][color=teal]tab[/color][b].htm[/b]"  I don't understand how they are keeping these variables separate without something like a / (forward slash) between them.  I also don't know how they tack on a .htm on the end of every URL

here is my .htaccess file  (note:  I don't care about separating out the artistLetter as ultimate-guitar has done.  root.php figures out what do do with the variables)

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteRule ^([^/\.]+)/?$ root.php?artist=$1 [L]
RewriteRule ^([^/\.]+)/([^/\.]+)/?$ root.php?artist=$1&title=$2 [L]
</IfModule>

does anyone know how to generate this fake URL and retrieve the variables inside it ([color=red]title[/color], [color=orange]version[/color], and [color=teal]type[/color]) while adding a .htm at the end?

Many thanks guys :)