How iterate records

Hi,
I have a problem of plpgsql usage. When I iterate through dynamic query, like this:

FOR my_/record/ IN EXECUTE /text_expression/ LOOP
    /statements/
END LOOP;

I am not able to construct expression, which can get value for each 'item' of my_record, something like my_record[3] or
get_item(my_record,3), without knowledge about real names of record pieces. I know that it is not the goal of this
language,but my goal is to implement some lite functions returning XML rather then something else... 

pajout