This part of the file is written from the subroutine SYSGEN. It states the periodic boundary specification, the cell vectors and volume (if appropriate) and the initial configuration of (a maximum of) 20 atoms in the system. The configuration information given is based on the value of levcfg in the CONFIG file. If levcfg is 0 (or 1) positions (and velocities) of the 20 atoms are listed. If levcfg is 2 forces are also written out.
For periodic systems this is followed by the long range corrections to the energy and pressure.