How to copy contents in STL

Hi,

I want to know how this stl code work, does it copy the content of one DB to another and may i get explanation on how the STL code achieve it.

Why is the IN, OUT, INOUT parameter not appearing when this stl function is called.

Pls find attached image below thanks in anticipation.

Here is the function when called in 0B1 else where

Pi 

The block copies fixed blocks. From DatabusWrite to DatabusRead. It does not  requires any parameters then.

It does it by building ANY pointers to blocks of data to be copied and then call system block copy function.