RSET rsbetween_create( NMEM nmem, int key_size,
int (*cmp)(const void *p1, const void *p2),
RSET rset_l, RSET rset_m, RSET rset_r, RSET rset_attr,
RSET rsbetween_create( NMEM nmem, int key_size,
int (*cmp)(const void *p1, const void *p2),
RSET rset_l, RSET rset_m, RSET rset_r, RSET rset_attr,