Cash-Balance Proposed Regs

[JAY21]

The proposed regs on cash balance plans gave us new market rate of return options but left some unanswered questions in my mind particularly with regards to what interest credit for FUNDING purposes you would use to project the account balance to NRA if say you have a market return that is negative for the year or even say a modest 1%. Is this an actuarial assumption that can/should be different than the actual rate of return credited to the theoretical accounts for the year ? Any ideas/opinions ?