The .dpl file format is the preferred output format for
DELAUNDO. It is a rather compact ASCII file that can be
read into dplot and xcfd plot softwares. Although the 
solution is given in the nodes, vertex centered codes 
can use corner information and a separate solution file.

The .dpl file lists:

unstructured grid data by Delaundo 4.0
    (a first line with a header.)
    8 0 1
    (the number of cells, and two integer placeholders,
     e.g. number of previous iterations and the variable to
     check the convergence.)
3      9     4     5      13     6     4       1
3      9     1     2      10     4     5       2
3      4     2     3      11    12     4       3
    (for each cell, the number of corners, the
     nodes at each corner in counterclockwise sense,
     the neighboring cells with neighbor #1 being
     opposite node #1, i.e neighbor #1 and this cell
     share nodes #2,3, and a running counter.)
3      9     2     4       3     1     2       4
3      9     8     1       9     2     8       5
3      9     5     7       7     8     1       6
3      7     5     6      14    15     6       7
3      9     7     8      16     5     6       8
     9
    (the number of nodes.)
 1. 1. 1. 1. 0. 0.
    (four reference freestream state quantities and two
     float placeholders, e.g. reference normalizers for
     L2 and Linfinity norms for restart.)
  0.3000000E+01  0.0000000E+00 1. 1. 1. 1.     1
  0.3000000E+01  0.2000000E+01 1. 1. 1. 1.     2
  0.3000000E+01  0.3000000E+01 1. 1. 1. 1.     3
  0.2000000E+01  0.3000000E+01 1. 1. 1. 1.     4
    (for each node, the x and y coordinates,
     four state quantities, and a running counter.)
  0.1000000E+01  0.3000000E+01 1. 1. 1. 1.     5
  0.0000000E+00  0.3000000E+01 1. 1. 1. 1.     6
  0.0000000E+00  0.2000000E+01 1. 1. 1. 1.     7
  0.0000000E+00  0.0000000E+00 1. 1. 1. 1.     8
  0.1267948E+01  0.1000000E+01 1. 1. 1. 1.     9
  4  4   1   3   6   8   2   4   3   1
    (the number of boundary segments, the number of corners
     between boundary segments, the node numbers at each
     corner and the left oriented boundary name for each
     corner, i.e. the name of the boundary oriented with
     the domain to the left, having this nodes as first
     node.)
   1   2
    (For each segment the number of nodes along the segment
     and the name of the segment.)
   1   8     5       9
   (for each boundary face, the two forming nodes, the
    interior neighbor and a counter.
    Note that the orientation of any face is changed
    when viewing it from the other cell that shares the face.
    For boundary cells this means that traversing from the
    first listed node of a cell to the second, the domain is
    to the right.)
   2   4
   2   1     2      10
   3   2     3      11
   3   3
   4   3     3      12
   5   4     1      13
   6   5     7      14
   2   1
   7   6     7      15
   8   7     8      16
  0 -1
    (an indicator that there are no outer boundary faces (see
     dplot for definition) and a bogus boundary name.)