ASCII Trajectory Files

The first line of a trajectory file defines the number of comment records. This is followed by “header" records.

CORD     1000   1000  0      5932  0.204548E-01
^ type   ^begin ^skip ^void  ^number of atoms
                                   ^ timestep

  10000.0       800.000    12Z6      
  ^ scale       ^ offset   ^ format

174      1     21     23     27     28     39 
^number of free atoms
         ^      ^      ^      ^     ^ ... Ids of free atoms

Header records are in turn followed by coordinate sets separated by the string CORD. The first coordinate set contains all atoms. The subsequent coordinate sets contain only the selected atoms (see, for example, the CSELection statement in Section 11.1.6).