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variable: $clustarea -- minimum cluster size mm^2
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default: 300.0

"NormSamp, Clust Controls" parameter.  To adjust,
access pop-up by L-click on "label:" (bold).

This variable controls the minimum cluster size
(in mm^2) for a cluster to pass the cluster size
filter in surfclust (run by "CS" button on "val:"
line).

This is passed directly to surfclust as follows:

  surfclust ... -minarea $clustarea ...

Use the command line utility, randsurfclust, to
determine the correct area here.  See

  Help -> Cross Session Spherical Average

for more detail on how to do this.
