Editing vb:raw post.message

[yukirina]

Hello, I wish to do some automatic word find and link replace (using preg_replace) any given word found on the post. I figured that in the templates, vb:raw post.message is the variable that contains every message per post, but I don't know where in the php file affects this variable. What is the final parsed variable in the php file before being pushed onto vb:raw post.message, and what php file is it located in?