What's the definition of 'pathline' in Fluent
 

When I do an unsteady case, for each time step, I display the pathline of particles injected at a certain face. Does the parthline just represents the streamlines at the current time, not the trajectory of particles for my unsteady problem?

I want to ask the definition of 'pathline' in Fluent. Is it only calculated by the velocity field at the current time? Does it only converge with streamlines at current time and is it nothing to do with the velocities at previous time?

If I want to see the trajectory of particles of my unsteady problem, do I have to to use DPM? Can I use 'pathline' to do this?