Events of Default (Early Termination Payments) - ISDA Provision
The effect of this is that in closing out an ISDA, the first step is to terminate all transactions to arrive at a Close-out Amount for each one, then figure out if there were any Unpaid Amounts that were due under Transactions but had not been paid at the time the Transactions terminated. The close out happens under Section 6(e) of the ISDA Master Agreement itself and the recourse is to a net sum. Netting does not happen under the Transactions — on the theory of the game there are no outstanding Transactions at the point of netting; just payables.
Therefore, if your credit support (particularly guarantees or letters of credit) explicitly reference amounts due under specific Transactions, you may lose any credit support at precisely the point you need it.
Which would be a bummer.
Further commentary on the Guarantee page.