int cd_PutUserData(UBYTE *filenm,int uindex,struct ud_Data *udata);
   
   ---
   
   Purpose: puts userdata in user datafile.
   
   Results: updated 'User.data' file + sets return code to:
            
                    OK           - all ok
                    EFILE_OPEN   - file open error
                    EFILE_SEEK   - file seek error
                    EFILE_WRITE   - file read error
                    
      
   Usage  : rc = cd_PutUserData("User.data",index,&userdata);
            if(rc != OK)
            {
                /* error */
            }