how to display content depending on root category ?

how to display content depending on root category ?



I would like to create a HTML block in the products blocks section …



however i would like to display different content depending on which

root category the product is from … and keep displaying the same content

on all the product that are in any or its subcats .



im thinking maybe there is a variable i can check to see what the root cat id is for the selected product…



what would be nice is if i could use the products block feature and tell it to display

that block on all products from xx cat and subcats …