TradeMAE
Maximum adverse excursion, the maximum price movement in adverse direction of the trade. Only valid when the trade is open.
http://zorro-trader.com/manual/en/trade.htm

Why is it only valid when the trade is open? It's not obvious to me.

Also, what are the units of TradeMAE values?

In practice, I see very small values for closed trades in GBP/AUD
0.007787
0.000064
0.005661
What are the units of these values?

The unit is asset price movement. But I don't know either why they are not valid anymore when the trade is closed - I'll check.

Ok, they remain valid in the current Zorro version, so you can read them even after the trade is closed. They lost their content in an old version because the variables were reused for other content.

Great. Thanks!

How would I convert that into units of the account currency? so it has the same sense as TradeProfit

With the "TradeUnits" variable.