# A box with eight points in 2D, no attributes, one boundary marker.
8 2 0 1
# Outer box has these vertices:
 1   0 0   0
 2   0 3   0
 3   3 0   0
 4   3 3   33     # A special marker for this point.
# Inner square has these vertices:
 5   1 1   0
 6   1 2   0
 7   2 1   0
 8   2 2   0
# Five segments with boundary markers.
5 1
 1   1 2   5      # Left side of outer box.
 2   5 7   0      # These four segments enclose the hole.
 3   7 8   0
 4   8 6   10
 5   6 5   0
# One hole in the middle of the inner square.
1
 1   1.5 1.5