Quick question for a Smarty/PHP guru

I know very little about Smarty or PHP but I assume one or the other is used to grab the product description and use it as the meta description if the meta description field is left empty.

What Im trying to do is limit the # of characters that it uses when it grabs the description. Right now I think its 400ish but Id like to change it to 200.

Any takers?


|truncate:200 to the end of the variable