Layouts data tags in blog post

After having worked with the blogger templates for some time I got the idea that it might be possible to use the template tags in the blog posts and not just in the template. What happens if I insert:

<data:blog.pageTitle xmlns:data='http://www.google.com/2005/gml/data' />

that's right - nothing happens!, which must be because the blog posts are inserted after the pass by the template engine.