username and sub-domain same - Restrain subdomains/subdirectories

[rosegarden]

I am not sure if this is a bug or not

I have applied under "Restrain subdomains/subdirectories" the word "blog" which i shall be installing wordpress

I dun quite understand what this restrain function is for? Is it to block something?

I tried to register a member using the username "blog" and was successful.

Both following URL works for this user and lead the user page, so will this is a conflict for xxx.com/blog/index.php in the future for my wordpress?

xxx.com/blog
xxx.com/blog/

I created a html page and create a directory "blog" and upload this page. The page is not able to be viewed, it will get divert to the user page.

Please advise how i create a wordpress blog at a directory or is there something i need to add at the .htaccess

I tried applying the following but it did not work

RewriteCond %{REQUEST_URI} !^/blog