x.rea
-2                         spatial dimension (if negative dump .re2 file)
1                         number of fields
#
#=======================================================================
#
box_1
-6 -3 1                nelx,nely,nelz (negative --> auto spacing)
0.0  5.00 1.10           x_0  x_1 ratio
-1.0  -0.5   1.25           
W  ,O  ,W  ,   ,   ,     bc's  ! west,east,south,north,bottom,top 
box_2
-6 -3 1                nelx,nely,nelz (negative --> auto spacing)
0.0 5.00 1.10           x_0  x_1 ratio
-0.5 0.0  0.8            
W  ,O  ,   ,   ,   ,     bc's  ! west,east,south,north,bottom,top 
box_3
-6 -4 1                nelx,nely,nelz (negative --> auto spacing)
0.0 5.00 1.10           x_0  x_1 ratio
0.0  3.0  2.20          
   ,O  ,   ,SYM,   ,     bc's  ! west,east,south,north,bottom,top 
box_4
-4 -4 1                nelx,nely,nelz (negative --> auto spacing)
-5.0 0.0 1.00           x_0  x_1 ratio
0.0  3.0  2.20          
v  ,   ,W  ,SYM,   ,     bc's  ! west,east,south,north,bottom,top