I think it is the broker id. I believe it is only available in the full "Iress" version used by brokers. Haven't seen it myself.
Nugett,
Probably should have clarified. Yes Commsec's settlement terms are T+3 i.e. on the third day after the trade, the transaction is settled. So if I bought yesterday 17/3 it gets settled on 19/3. So you don't need funds in your account to buy stock. T+1 refers to traders who try to buy and sell on the same day so that on the third day, the buys and sells net off and they do not have to pay commsec anything (hopefully assuming they made a profit).
HTX Price at posting:
17.0¢ Sentiment: Hold Disclosure: Held