Motion paths are an advanced feature of Panda3D, and they are discussed later. Still, motion paths have their own intervals. A motion path interval is much like a function interval in that there are no additional parameters other than the motion path and the NodePath it is affecting.
intervalName = MopathInterval("Motion Path Name", NodePath, "Interval Name")
Read more about Motion Paths.
Particle effects can be run from inside intervals as well:
intervalName = ParticleInterval(
"Particle Effect Name",
worldRelative = 1,
loop = 0 or 1,
duration = myDuration
Read more about Particle Effects.