The output files are named xxx_001.yyy etc., where xxx is the name of the input file (minus directory path) and yyy its extension (if present).
If num is given, only the model with the corresponding model number is extracted.
Everything before the first MODEL (except JRNL and REMARK records)
is copied to every file.
Everything between MODEL and ENDMDL is copied.
The MODEL records are replaced by a REMARK.
The ENDMDL records are replaced by END.
Everything after the last ENDMDL (including CONECT's) is discarded.
A MASTER record is not added.
If no inputfiles are given, their names are assumed to be xxx1.pdb, xxx2.pdb etc. and you will be prompted to specify xxx and the number of files.
Everything before the first ATOM record will be left out except for the
first model.
An END record MUST be present in every file (therefore it is added by the
script when missing).
CONECT and MASTER records are discarded.