Can someone write simple equation for FFO?

I’m flicking between FRA and Fixed Income (it appears in both books) trying to reconcile the definitions but I’m going round in circles.

FRA book : net income adjusted for non-cash items

Fixed Income book : net income from continuing operations plus depreciation, amortization, deferred income taxes, and other non-cash items

What are ‘non-cash items’ apart from depreciation and amortization? Deferred income counts as a non-cash item?

Income from Affiliate would be a noncash item.