sid=sion_open( ...,chunksize, &fileptr)                   
        
sion_get_locations(sid,&size,&blocks,&globalskip,&start_of_varheader,
                       &sion_localsizes,&sion_globalranks,
                       &sion_chunkcount,&sion_chunksizes);

loop: { 
   sion_seek(sid,rank,blknr,pos);
         
   fread(...,fileptr) 
}
sion_close(id);                                
