COMPND Fumarate with double bonds.
REMARK PDB file provided by Chris Hogue, edited and commented by Eric Martz.
REMARK
REMARK This file is to illustrate the rendering of double bonds by RasMol
REMARK 2.6 beta-2.
REMARK The doubling of bonds is shown only by the wireframe/stick
REMARK representation. In order to draw double bonds, the wires must not
REMARK be excessive in diameter.  Making the molecule larger by increasing
REMARK the size of the graphics window, or zooming >100%, can cause the
REMARK double bonds to revert to single.  
REMARK Double bonds are always shown with the plane they define parallel
REMARK to the viewing screen.  As the molecule is rotated, the bonds do
REMARK not rotate, so their doubleness can always be seen.
REMARK
ATOM      1  C           1       1.608   0.736   0.700  1.00  0.00
ATOM      2  O           1       2.812   0.584   0.556  1.00  0.00
ATOM      3  O           1       1.176   1.600   1.524  1.00  0.00
ATOM      4  C           1       0.660  -0.084  -0.080  1.00  0.00
ATOM      5  C           1      -0.660   0.084   0.080  1.00  0.00
ATOM      6  C           1      -1.608  -0.736  -0.700  1.00  0.00
ATOM      7  O           1      -2.812  -0.584  -0.556  1.00  0.00
ATOM      8  O           1      -1.176  -1.600  -1.524  1.00  0.00
ATOM      9  H           1       1.028  -0.816  -0.780  1.00  0.00
ATOM     10  H           1      -1.028   0.816   0.780  1.00  0.00
TER      11              1
REMARK
REMARK The first atom in each CONECT record (line) is connected to each of
REMARK the other atoms in the record.  The 2nd through Nth atoms in each
REMARK record are not connected to each other by that record.
CONECT    1    2    2
CONECT    4    5    5
CONECT    6    7    7
END
REMARK A double bond can also be specified with two CONECT records, e.g.
REMARK CONECT    1    2
REMARK CONECT    1    2
REMARK In this case, both must be specified in the same direction.  That
REMARK is, this doesn't work:
REMARK CONECT    1    2
REMARK CONECT    2    1