ok, I see what's going on.
you're putting stuff in a session value, which contains (hopefully valid) xHtml.
But the internal mechanism for handling session values (in tags) means that the contents of the session value is encoded.
I have added a new tag to 6.34,
<!-- Net:x:whatever -->
:x works like :s, except that you are explicitly telling it _not_ to encode the contents. This means (just like in all the places where you turn on "allow xHtml") that you are responsible to make sure the contents are indeed valid xHtml.
cheers
Bruce