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entry variable: $sfthresh -- statmask hard threshold
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default: 0.3

This entry is only visible if overlaymaskflag is
ticked (to left of "mskn:" or "mskup:").

If the stat mask for a pixel is below this
number, the *value* (e.g., coef) is masked to
background.

The units of this mask threshold ($sfthresh) will
*not* in general be the same as the units of the
amplitude thresh ($fthresh).

See $fthresh and $fmid help for more details.
