ncs strict {<ncs-strict-statement>} end

<ncs-strict-statement> :==

  initialize
  --{Turn off strict ncs constraints and delete any information
     about previous entries.}
  skew <ncs-strict-skew-statement> end
  --{Define skew matrix frame and origin. Defaults=identity}
  xncsrelation <ncs-strict-ncsrelation-statement> end
  --{Operator for generating non-crystallographic symmetry 
     for structure factor calculation and inter-molecular 
     interaction energy. The identity operation is optional and
     is always assumed.}
  ncsrelation <ncs-strict-ncsrelation-statement> end
  --{Additional operators for calculation of ncs non-bonded 
     interactions. Must be given after all xncsrelation operators.
     If x-ray terms are not in use, all ncs operators may be given here.}
  ?
  --{List current ncs operators.}