Where what valve?

I have looked at all the diagrams and numerous other engines on the web. Where does the small hose on the valve marked with a red * go? Do I even need it? 91CRX HF w/ b16a

http://files.automotiveforums.com/gallery/watermark.php?file=/503/92815valve2.jpg

I have the same vale and I plugged it and haven't had any problems