Hi, freesurfer community

I'm Francisco Robles, from the Instituto Nacional de Neurología y Neurocirugía in México city. I am using FS-Fast to analyze some event-related fMRI. My problem is how to use the paradigm file because I need to exclude some images from my analysis. The situation is that I have a paradigm of 3.5 secs of stimulus and a variable quantity of Null/fixation. But from those 3.5 secs of stimulus, I only want to analyze the last 1.75 secs. The opseqt file I've got goes like this:

0.0000    2    3.500   1.0000          var1
3.5000    4    3.500   1.0000          var3
7.0000    4    3.500   1.0000          var3
10.5000    3    3.500   1.0000         var2
14.0000    0    1.750   1.0000         NULL

And I edited it to look like this but I really don't know if it is the right way to do it:

1.75      2    1.75    1    "var1"
5.25      4    1.75    1    "var3"
8.75      4    1.75    1    "var3"
12.25    3    1.75    1    "var2"
14.00    0    1.75    1    "NULL"

So I put in the column of stimulus onset, the time point I want to analyze and in the duration column, only the quantity of time I want to analyze.

But I've seen in mkanalysis-sess.new on wiki, that there is a flag -tpef [filename] for the command selxavg3-sess that allows to exclude certain files according to a time-point, but I don't know how to do it, how is the arrange of taht file, how many columns, how do I say to it that I only want the last 1.75 secs and not the hole 3.5 secs.
I am really lost, if anyone can help mw I will appreciate it a lot. Thank you all in advance.

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