Group 3d Mask
3D Mask - Mask according to object id or particles groupThis mask can be used with a 3D File with multiple objects in it, grouped in one mesh or with a Particles's groups.
Their function is to apply a 3D Modifier or a Field only on a specific object or a particle Group. Groups of particles can be defined through Particle Rule.
On the example below, you see the green particles emitted from Group  particles and colorized in Green. Theses particles have an "Increase Group" action ("Set Group" action in menu) that changes their Group to .
The Gravity field has a Group Selector Mask set as Single Selection on Group , which means that the gravity field will only have an effect on the second Group (, the green ones in this case).
By default the "single selection" parameter is uncheck which means that the mask will have an interpolated effect on several groups. That means that the lower group will be fully masked while the higer group will be fully affected, with a gradual progression in between.
Particles: Particle Rules - Generation sprite selector (with Collision condition).compo.