If you using an expert advisor or script in metatrader terminal you can find the parameter called "magic" or "magic number".
What does it mean?
Magic number is identifier for orders it helps for a robot to separate running orders from other expert advisors.
What magic number have manually opened orders?
By default orders opened from metatrader terminal have magic number equal 0.
Where I can find the parameter?
Usualy this number placed in a forex robot or script settings near the top of the list. Press right mouse button on a chart, choose Expert Advisors Properties menu.
Or just press F7 on a keyboard.
Double click on the parameter and set your identifier.
What if I can't find this option in the settings?
It means developer who made this soft already set the magic number in a code.
How I should configure it?
In most cases you can leave the parameter by default.
If you want to use several expert advisors in the one trade acount make sure you've set unique magic numbers for the robots.
If you want to use recovery manager or trade panel for an expert advisor magic number should be matched to the expert advisor.
If you want your expert advisor or a script do manage manually opened orders you must set the magic number to 0.