Links to open in parent window ALWAYS

I need to customize the links for wordpress so when a link is entered wordpress makes the link open in a parent window. What is the easiest way to do this?

We use wordpress in an iframe for a very small part of a web site. We want to ensure that a user entering a new comment into wordpress does not have to specify the html code for opening a link in parent window. It is to say we want PARENT window to be default for all links.