[selection] Selection.setBaseAndExtent

I noticed that some websites use selection.setBaseAndExtent [1]. According to what limited documentation I could find, it works similar to selection.extend. Is there any intention to standardize this, or is it made obsolete by selection.extend?

Ben

[1] http://stackoverflow.com/questions/985272/jquery-selecting-text-in-an-element-akin-to-highlighting-with-your-mouse