This is a possible parameter for NONATOMIC_BLOCK. When used, it will cause the NONATOMIC_BLOCK to force the state of the SREG register on exit, disabling the Global Interrupt Status flag bit. This saves on flash space as the previous value of the SREG register does not need to be saved at the start of the block.

Care should be taken that NONATOMIC_FORCEOFF is only used when it is known that interrupts are disabled before the block's execution or when the side effects of disabling global interrupts at the block's completion are known and understood.