Position trading is trading based on your overall exposure to a currency pair. Your position is your average price for a currency pair. For example, you might make a short trade on EUR/USD at 1.40. If the pair is ultimately trending lower but happens to retrace up, and you take another short at say 1.42, your average position would be 1.41. Once the EUR/USD drops back below 1.41, you will be back in overall profit.