[NTLDR]

In register.php find:

PHP Code:

        eval('$errors[10] = "' . fetch_phrase('username_semicolon', PHRASETYPEID_ERROR) . '";');
    } 


Add after:

PHP Code:

    // prevent all caps username
    if ($_POST['username'] == strtoupper($_POST['username'])) {
        
        eval('$errors[15] = "' . fetch_phrase('username_allcaps', PHRASETYPEID_ERROR) . '";');    
    } 


Add a phrase called username_allcaps in the front end error message group with the error message to show if a user enters an all caps name.