.htm on PAGES
Appends .htm to the URL of PAGES when using permalinks
Tag do plugin: htm
Custom Page Extensions
Allows you to add a custom extension to your page URLs. This only affects pages…
WP Page Extension
Converting an old HTML, PHP, or ASP site to WordPress? WP Page Extension will let…
.htm and underscores on PAGES
Appends .htm to the URL of PAGES when using permalinks and swaps dashes with underscores