Mt4 volume indicator?

i was under the impression that volume was immeasurable in forex, yet theres an indicator for volume for mt4? how does it work?

Tick volume. The easy explanation is, it’s the amount of times price changes in a given period. Not volume of units traded like equities are.

can it be used for pattern validation just as equity volume? im assuming not since i havent seen many people use it…

http://forums.babypips.com/newbie-island/41475-supply-demand-vsa-wyckoff-petefader.html