rmsd0:   RMSD TYPE=OPTIMAL REFERENCE=test0.pdb
rmsd1:   RMSD TYPE=OPTIMAL REFERENCE=test1.pdb

sum: COMBINE ARG=* PERIODIC=NO

RESTRAINT ARG=sum AT=20.0 KAPPA=1.0

PRINT ...
  STRIDE=1
  ARG=*
  FILE=COLVAR FMT=%6.3f
... PRINT

ENDPLUMED

text here should be ignored
