Thread: how to pick amplitudes

Dear all,
I'm trying to pick the amplitudes of the s and p arrivals. What I've been
done so far is picking them using the command ppk and then positioning the
cursor and pressing m. That draws a little box around the portion of the
graph that contains the arrival. I thought SAC will store the info in the
header but I can't find any variable with information of this specific
portion of the graph. I'm new using SAC so I guess I am missing something
important here. Do I have to set a blackboard variable before hand? I am not
looking for the depmin and depmax just for the amplitude value of the p, s
and a pre-s phase.
Any input will be very appreciated
Cheers,

Denise Fernandez