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tcl var: $criterion passed to fill_nearest_vertices
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keyboard equivalent: none

The unlabeled entry between the "N" and "A"
buttons (lower right) specifies the number to be
passed to the fill_nearest_vertices function as
the criterion argument:

  fill_nearest_vertices <type> <criterion>

Its meaning depends on which type is selected:

  N (fillneartype=0: number) -- fill to vertex count (n)
  A (fillneartype=1: area) -- fill to orig area (mm^2)
  R (fillneartype=2: radius) -- fill to radius (mm)

The default value (250) makes sense for either
number or area, since each vertex accounts for
approximately 1 mm^2.

N.B.: the radius of an equivalently-sized region
is approximately 10 mm.
