Age

3D Mask  -  Depends on the age of a Particle to mask a modifier / effect

On the example Image, all particles are masked by an Age Mask.

This can also be achieved with a lot more options by using a Function set as Age.

This mask allows to use Field or 3D Modifier only on a defined period of a Particles lifespan. If you want for instance for gravity to affect only dying particles, just set a function mask as Age over a Gravity and make it work only on the end of the lifespan. Here is an example:

    Oil.createObject("AgeGeometryMask")