Variation margin — amount paid (obtained) by trading participant to another participant in connection with the change of a monetary obligation in one position due to adjustments to market value. In Forex it’s all changes at the open position relative to the open price. For example, the position is opened on the first day at 3000.e. turns into 5000.e. variation margin in 2000.e. The next day the position becomes unprofitable and drops to 4500.e. variation margin — 1500.e.