Action: Unstick From Source Object
This action will 'unstick' particles emitted from a source object and which were stuck to the object on emission.
The Action's interface looks like this:
Unstick From Source Object
The interface is extremely simple and only has this one setting. If a particle was stuck to its source object on emission (see the Emitter object for details) then it will remain stuck until unstuck by this action.
Note that this is quite different from the Cover/Target modifier which moves particles to an object and sticks them to it - the Unstick action only affects particles which were stuck to the object they were emitted from. It has NO effect on the Cover/Target modifier.
Drag the particle Group object(s) you want to be affected by the modifier into the 'Groups Affected' list. If the list contains at least one group, groups not in the list will not be affected. But if no groups are in the list, all groups are affected.