Modifiers tab menu.
If enabled, the emitter will only be affected by modifiers/deformers/effectors which are child objects of the same System object as the emitter.
By default, any modifier in the scene will act on any emitter and they do not have to be added to this list.
xpEmitter_Modifiers 02_v02.mp4
In this animation, xpGravity and xpTurbulence are dropped into the Objects field of the Modifiers tab, in order that they can be enabled/disabled from there.
To prevent a modifier from working on a specific emitter you can drag the modifier into the list and click the icon to change it from a yellow check mark to a blue dash.
Alternatively, you can enable Only in Same System.
This will restrict the modifiers acting on the emitter to those in the same System object hierarchy.
Deformers and effectors are handled differently.
They will only work on an emitter if dragged into this list with a yellow tick icon or if they are made a child of the emitter in the Object Manager.