How to set convergence criteria?

Hi everyone,

I'm working with the CFD and heat transfer modules and I'm not able to figure out how to set the convergence crtieria.
I'm performing a stationary study with a relative tolerance of 0.001 (defined in Stationary Solver --> General --> Relative Tolerance). I'm using a segregated solver with two steps, and each one of them uses an iterative solver.
I have got a couple of questions:
1) In the settings of the Segregated Solver, what is the difference between "Termination technique" and "Termination Criterion"? I mean, I know what termination technique means, I can't just figure out what termination criterion is, and why if I choose Solution or residual it asks me to define a residual factor.
2) In the settings of each segregated step, why does Comsol ask me to define again the termination technique and criterion? Shouldn't they be the same of the general segregated solver?
3) In the settings of each iterative solver, what does "Factor in error estimate" mean?

Thanks for any help you may provide.

- Davide