.PS
h = .5i
dh = 0.02i
dw = .1i
[
   Ptr:[
      boxht = h; boxwid = dw
      A: box
      B: box
      C: box
      box wid 2*boxwid "..."
      D: box
      ]
      Block: [
         boxht = 2*dw; boxwid = 2*dw
         movewid = 2*dh
         A: box; move
         B: box; move
         C: box; move
         box invis "..." wid 2*boxwid; move
         D: box
      ] with .t at Ptr.s - (0,h/2)
      arrow from Ptr.A to Block.A.nw
      arrow from Ptr.B to Block.B.nw
      arrow from Ptr.C to Block.C.nw
      arrow from Ptr.D to Block.D.nw
   ]
   box dashed ht last [].ht + dw wid last [].wid + dw at last []
.PE
