pos_t
int vs_sm_fill(SCR *, recno_t, pos_t);
int vs_sm_position(SCR *, MARK *, u_long, pos_t);
vs_sm_position(SCR *sp, MARK *rp, u_long cnt, pos_t pos)
vs_sm_fill(SCR *sp, recno_t lno, pos_t pos)