Last Bar Used

Both trading systems and alerts have these fields, but they are updated slightly differently. For trading systems, only when the entry rules are checked (i.e. a trade is not already open) will the date be updated. For alerts, the date is only updated when an alert wants to fire.

These fields ensure that only fresh price data is being used for entry calculations. Here's the scenario that these fields try to avoid:

1. A new bar completes.
2. ATM checks the entry rules and finds that they are true. ATM places an order.
3. The order is taken up. This trading system is in a trade.
4. The price goes in exactly the wrong direction, and the stop loss is taken out very quickly.
5. ATM checks the entry rules and finds that they are true. ATM places an order.

The thing is that the bar being checked in steps 2 and 5 are the same bar. The trade exited so quickly that there wasn't enough time for the next bar to complete (which is a likely outcome if you are using Hourly, Daily bars, etc).

So ATM would have placed two orders based on the same bar. Generally that's not a good thing, hence these fields. And hence the reason they are only updated when the entry rules are checked.

If you want to allow it, you can put a tick-mark in the "If the trade is exited before the entry bar is completed, allow re-entry in that same bar" field.

This is another way to pause a system for a while - by editing these dates to be somewhere in the future (and no tick-mark in the checkbox).