In the symbol-properties-database.csv file, I see two columns that I don't understand, relating to forex: contract_multiplier and lotsize. No idea what contract multiplier is but in my mind, lot size would represent the USD amount notional of 1 contract, i.e. $100,000. But in the case of FXCM, lot size is set to "1000" and in the case of Oanda, it's "1".

Why the difference? And what do these two columns represent? How should I translate this information into how many "traditional" lots I am buying and selling?