  This paper shows that a necessary condition for regular identification of the OLIVA is also sufficient for  existence of an IV estimand in a linear IV model.
<meaning-changed>   This paper shows that a necessary condition for regular identification of the OLIVA is also sufficient for  existence of an IV estimand in a linear IV model.
 The OLIVA is invariant to the distribution of the instruments. This paper shows that a necessary condition for regular identification of the OLIVA is also sufficient for existence of an IV estimand in a linear IV model.