rewrite rule to convert from .htm to .html

[Omzy]

I currently use the following rule to rewrite .php to .htm

 

RewriteRule ^(.*)\.htm$ $1.php

 

I now want to change this so that it rewrites .php to .html, but also add another rule to redirect any existing .htm urls to .html (must be a search engine friendly/301 redirect).

[premiso]

RewriteRule ^(.*)\.html$ $1.php [L]
RewriteRule ^(.*)\.htm$ $1.html [R=301,L]

 

But why not just rewrite .htm and .html to php permanently?