By clicking on a link in the (index) page in the left frame this text in the right frame will be replaced with the page linked to. Here there is a functional connection between the two frames in a technical sense.
Note the difference with Multiple Viewing, where you click and view in the same left/right or top/bottom frame, and where there is no functional connection between the two frames in a technical sense! To start this type of viewing you will have to push either the 'Horizontal' or the 'Vertical Multiple Viewing' button at the bottom on the far left of this frameset.
You may also opt for the Main Document in This Language being displayed directly in the present frame.