What is POD? What rights does the "mail to" registrant have?

Who may cash a Savings Bond that has three names listed on the face as follows: TO: Levi Doe, Mail to: Mary Doe, or: Reggie Doe (can the "mail to" person cash the bond - what if this is actually the person who purchased the bond)? If a bond is made out To: Mary Doe POD Levi Doe can either cash it? What is POD? If only two names are on a bond (with an "OR") can one of these people change the bond names to themself and someone else? I'm asking this in case of the death to one or any other reason owner wishes to change second name?

Tom's response

The "mail to" person is not a registered owner and can't cash the bond. If that person actually purchased the bond, a gift occured at that moment that can't be taken back.

If there are two names with POD (payable on death), the first person is the owner and the second is the beneficiary. The beneficiary can't cash the bond unless the owner dies. The owner can change the beneficiary whenever he or she likes with no consequences.

If there are two names with OR, they are co-owners. If one of the co-owners has died, the remaining co-owner can add someone as either co-owner or beneficiary.

If there are two living co-owners, you can change one, but it will create a taxable event.

My book has a lot more information about all the ins and outs of registration changes.