I'm confused by that broker data. Are these off-market trades...

I'm confused by that broker data. Are these off-market trades between only those specific entities, because they represent a zero sum game.

That doesn't seem to make sense, as there seem to be brokers missing from that list (such as ASB securities, which I use), so it doesn't appear to be an exhaustive list of all participants. Yet, at the same time, total buys equals total sells, as one would expect from complete market data.

Can anybody please clarify/explain? (perhaps my broker is actually listed there under a code that I don't recognise in this system??)