[Lynne]

You need to read the code to see what vB_Phrase is doing. First variable is the name of the phrasegroup, vbcms. Second is the name of the phrase, comment_thread_firstpost. Third is a variable being passed, $this->getPageURL(), in this case it would be {1} in the phrase itself. If you put another after it, $variable2, it will be {2}... another after it will be {3}:

PHP Code:

$message = new vB_Phrase('vbcms', 'comment_thread_firstpost', $this->getPageURL(), $variable2, $variable3); 


Then:

Variable 2 is {2}

You can view the page at [url]{1}[/url]

And, as I said before, I don't think it is called $article_title. Look at the code right before the phrase is created - there is NO variable called $article_title to use.