Would this work well for a random magic number??
// logic: AutoMagic is generated when placing an order. It is not reclaimed if terminal is closed and reopened though.
// StaticMagic can be used to continue an open order or used manually.
extern bool automagic? = True;
extern string staticmagic = "";
extern bool staticmagiconce? = True; //T=if staticmagic != "" and not in use then use on next order. if automagic = true then use, else no later trades.
extern string EA = "EA"; //useful if you want to see your EA trades from manual trades or other EA trades.
extern int TF = "60";
extern int TP = 45;
extern int SL = 90;
Comment( EA+"."+TF+"."+Symbol()+"."+TP+"."+SL+"."+Hour()+":"+Minute()+Seconds() ); //Example: "EA.60.EURUSD.45.90.900"
// You wouldn't want to close terminal because you would have to manually enter the magic to control open orders
//but why would you close it in the first place?
See also https://www.mql5.com/en/forum/143514