>Again thanks. I will try it in the morning when I get to work. General question - how is one to know that the Prt_info_1 stru does not need to be defined? Where does this info reside?

Basically, you have to define and fill structures and other input parameters of the function. For output prameters-structures you just provide buffers of requered size and funcion fills them. To access the elements of such structure you can map structure definiton to it or acces them by there offset and size. The struct class allows you to do such mapping. The Heap allocation class by Ed Rauh uses second approch, I believe .