But before we move on, let me address one issue immediately which is the criticism leveled at using volume in the world of spot forex. We all know there is no currently central exchange in the spot market, and as such we therefore have to turn to an alternative measure of volume, which is tick activity, and is a proxy for volume. My own view, and proven over many years, is that this volume works perfectly well, and in exactly the same way as in other markets. After all, volume is simply a measure of activity or a lack of activity, and if activity is very high or very low, then this signals participation or a lack of participation by the institutional market makers.
Coulling, Anna. Forex Trading Using Volume Price Analysis: Over 100 worked examples in all timeframes (Page 15). . Kindle Edition.