I agree with Irifidel actually I don't think it should be allowed to target sources through the macro system.. that's just making the system too easy for botting. It's not really hard to use a single click to select sources, and if your harvest is > 200 you can't benefit from macroing, or you'll be digging spots with low source content anyhow.
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~minouHigh Officer, Spiritus Artificis
Former Officer, High Officer and Leader, Reapers of the Dark