Sorry, I pushed send on that last email a little too quickly ... i should have dug a little deeper before posting here.
I now realize that getParentCategoryTree() is in fact retreiving the data i expected. It looks like it is storing the tree in a multidimensional array. Each parent category is stored in a key and its value is an array of its own parent categories.
So my question is ... Is there a built in mediawiki function that can take the results from getParentCategoryTree() and produce a list or do i need to do this manually?
And ... is getParentCategoryTree() the most efficient way (maybe it's the only way?) to retrieve the category tree for an article?
thanks again