To all nurses working in VA long term care facilities.

I'm a VA nurse working in a 240 bed VA Nursing Home Care Unit. Our DNR policy is, the pt has a DNR order that is valid for 90 days. When the order expires, it has to be renewed. I'm wondering if this policy is the same throughout the VA system. Is this the policy where you are employed? And my next question is, why does this order expire after 90 days???