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<p>
This plugin reads and writes the "DCD" binary trajectory file format
used by 
<a href="http://www.charmm.org/">CHARMM</a>,
<a href="http://www.ks.uiuc.edu/Research/namd/">NAMD</a>, 
and 
<a href="http://atb.csb.yale.edu/xplor/">X-PLOR</a>.

The plugin performs automatic byte
swapping to correctly read files written on machines with different endianness.
The plugin supports reading of X-PLOR files, Charmm with fixed atoms
and unit cell information, and NAMD files with fixed atoms and unit
cell information.  The DCD plugin writes trajectories in Charmm 24 format
with unit cell data and without fixed atoms.

<p>
<h3>Some basic DCD binary trajectory format specifications:</h3>
<p>
There's a description of the
<a href="http://atb.csb.yale.edu/xplor/">X-PLOR</a>
variation of the
<a href="http://www.lrz-muenchen.de/~heller/ego/manual/node93.html">DCD format here</a>:
<p>
The DCD format is structured as follows (FORTRAN UNFORMATTED, with Fortran
data type descriptions):
<pre>
HDR     NSET    ISTRT   NSAVC   5-ZEROS NATOM-NFREAT    DELTA   9-ZEROS
`CORD'  #files  step 1  step    zeroes  (zero)          timestep  (zeroes)
                        interval
C*4     INT     INT     INT     5INT    INT             DOUBLE  9INT
==========================================================================
NTITLE          TITLE
INT (=2)        C*MAXTITL
                (=32)
==========================================================================
NATOM
#atoms
INT
==========================================================================
X(I), I=1,NATOM         (DOUBLE)
Y(I), I=1,NATOM         
Z(I), I=1,NATOM         
==========================================================================
</pre>

<p>
and the following describes the difference between X-PLOR
<a href="http://www.ocms.ox.ac.uk/mirrored/xplor/manual/htmlman/node230.html">and CHARMM formats</a>:
<p>
Binary Trajectory Files
<p>
The file format is identical to the CHARMm-DCD format (Brooks et al. 1983,
which can be read by QUANTA  and a variety of other programs. The only
exception is that the number of coordinate sets written to the trajectory
file is explicitly written into the header of CHARMm-DCD files, whereas  
XPLOR writes a zero instead.
<a href="http://www.bio.unizh.ch/docu/acc_docs/doc/charmm_principles/Ch04_mol_dyn.FM5.html#678927">Brief CHARMm format description</a>

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