L2 alternative FFO&AFFO

FFO计算是从accounting net earnings 出发，经过非付现和非经常损益调整得到FFO，再扣减non cash rent adjustment 和 recurring maintenance-type capital expenditures and leasing costs 得到AFFO。我的疑问是FFO计算是从accounting net earnings 出发，accounting net earnings中已经扣减了operating expenses了，而计算AFFO又减一次recurring maintenance-type capital expenditures and leasing costs ，这相当于AFFO的计算从accounting net earnings 出发，减了两遍expenses吗，这样很不合理啊。