====== S Command ======

S,<num>,<group>,<elem>,<bbc>,<disp>,<force>

This command adds nonlinear properties to springs. This command does not add any element to the model. This command adds nonlinear model information to a spring defined with [[com:E]] command.    

  * num - nonlinear spring number 
  * group - group number
  * elem - element number
  * bbc - backbone curve number
  * disp - displacement type
  * force - force option