g to analog 
  channel.  Their fieldname's label is the label of the analog channel.
  Field CORNERS is a matrix (3,4) of double with the 3D coordinates 
  of the four corners of the force platform (expressed in the global frame).
  Field ORIGIN is a matrix (3,1) of double with the 3D coordinates 
  of the origin the force platform (expressed in the global frame).
  Field TYPE is an integer which indicate the force platform type.  For
  much information on this type, see the C3D documentation (www.c3d.org).