      to interpolate a state for BODY. 
 
   segid       is the segment identifier. An SPK segment identifier 
               may contain up to 40 characters. 
 
   gm          is the gravitational parameter of the central body 
               ( in units of kilometers **3 / seconds **2 ). 
 
   n           is the number of states and epochs to be stored 
               in the segment. 
 
   states      contains a time-ordered array of geometric states 
               ( x, y, z, dx/dt, dy/dt, dz/dt, in kilom