Encumbrances - Need clarification.

Hi All,

I am refering to the below mentioned document, where it says that the encumbrances on the PO gets relieved after the PO is delivered.

Impact of R12 Design in Procure To Pay Accounting Flow [ID 429105.1]

If that is the case,

Funds Available = Budget - Enc - Actual ( Let's assme Budget = 1000$  and we had a reserved PO for $500 )

Then funds available will be, Funds available = Budget - Enc - Actual  = 1000 - 500 -0 = 500

Now when the PO is delivered, if the Encumbrance gets relieved,

Funds available = 1000 - 0 - 0 =  1000.   

How can the funds available go back to 1000.