[Closed] Chinese battery charger instructions help

Just got my new charger from DX. A WF200, much better than the old basic model I had. Just a little confused over the switch on the side. It's a two position switch labelled "." and ".." as the top diagram helpfully explains. The instrucions only add that 'Upon discharge, switch located ".."' I don't think it is a discharge mode, I suspect it is to do with charging one or two batteries but it doesn't seem to make much difference. Any ideas?

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[url= http://www.flickr.com/photos/29543606@N00/8205897213/ ]P1080932[/url] by [url= http://www.flickr.com/people/29543606@N00/ ]nickjb[/url], on Flickr