A little icon on the top of a page is more or less the graphical version of the page header. It reassures you that you have reached your destination. Clicking on it takes you to the choice of topics on this page. So, if you have a slow connection, you are warned that this link will take a while. However, I limit my pictures to 30-40K approx.
Different browsers react differently to the uppercase links.
I have tested Netscape-versions 1 to 3. The image is displayed on full screen. Use the back-button to continue reading. A new window is opened and the image is displayed on full screen. Use the closer to resume to the page.