The limits you can set

Loss, profit, drawdown and trade count, all per session — and how long the lock holds.

Loss limit
Per session, in the account's currency, on the day's P&L — realized plus open. It is measured from the account's equity at the first reading of the session — normally just after 17:00 New York. On the day you arm the lock, or if the broker was unreachable at the roll, it is that later reading. Reached — at exactly your number, with nothing added — the account locks, so leave your own room: 475 for a firm rule of 500.
Profit target
The same measurement pointed the other way, and the same exact trigger — it stops you giving a good day back.
Session drawdown limit
How far equity, open position included (on Rithmic, measured only while flat for now), may fall before the account locks. It is a daily figure: it starts again at every session. What it is measured from is the choice under Reference point — the next two rows.
From the session high
The high is the highest equity reached this session, open profit included (on Rithmic, measured only while flat for now), and the floor rises with it.
From the session start
The floor sits a fixed distance below the session's first reading and does not move until the next session, so this works as a second daily loss limit.
Stop trailing once this session is ahead by
Only used from the session high. Once the session's high is this far above the session start, the floor stops rising. Measured from the session start, and reset with it. From the session start the floor never rises, so it has no effect there.
Trades per session
A count, not an amount. It counts the orders Tradeus places on this account from a strategy's alerts, including a plain buy or sell that only reduces the position. It does not count an exit alert, a trade you place by hand at the broker, an order you confirm from the pending list, or a trade copied onto this account as a follower. The account locks as soon as the order that reaches the count fills, and like any lock it then closes what is open — that order's position included. Set it one above the number of trades you want to keep.
How long it stays locked
Until the next session, or a fixed number of hours.
Close trades opened while locked
A trade you open by hand during a lock is closed again within seconds — on brokers where Tradeus can close positions, and only while that broker is connected.
Open P&L, and the broker that does not report it yet
The day's P&L counts the open position on Tradovate, TradeLocker, Capital.com, MetaTrader 5 and Alpaca. Rithmic does not report open P&L yet. So while a position is open on a Rithmic account, the lock cannot measure it: the Account lock page shows that account as not protecting right now, with the reason, and no limit on it can fire until the account is flat again. A flat Rithmic account is measured as usual — its realized P&L is all there is.
The day rolls at 17:00 New York
Not at midnight, and not in your own time zone. The daily limits, the trade count and the drawdown's high all start again there, because that is where the futures session rolls — the boundary most futures prop firms use.
This is not your firm's drawdown
Your firm's maximum drawdown usually runs across days — measured from the starting balance, or trailing the highest balance the account has reached — and it is the rule that ends the account. The lock's drawdown is a different, daily rule. It starts again every session, so an account can stay inside it each day and still lose enough across several days to reach the firm's limit. Tradeus does not track the firm's drawdown yet. Set the daily figures with the room you have left at the firm in mind, and read that number at the firm.

Also in Risk and protection