Resting State 3dClustSim

AFNI experts,

I am analyzing resting state data using afni proc py example 11 and am currently working on getting clustsim results for statistical analysis. I have two questions.

  1. Which mask should be used for 3dClustSim result?

  2. What is the difference between -fwhm and -acf?

Thank you in advance for your help,