The xpTrailsMod affects particle trails, to shrink or grow their length.

It is a more flexible option than using the Trails action to shrink the trails.

General tab

xpTrailsMod General tab menu.

Enabled

Checking this box enables the xpTrailsMod.

Mode

Set at Independent by default.

You can change this to Action-Controlled.

Independent Mode

In this mode, particles will be affected if they come into the field of effect of the modifier.

Action-Controlled Mode

When in the Action-Controlled Mode setting, the modifier will only act on a particle when told to do so by an action.

Operation

Set as Shrink, by default.

The other options are: Expand, Grow and Pulse.