cash costs

We have been talking about cash costs previously in relation to gold.

I came across the following:

C1 = operating cash cost (mining + milling + administration)

C2 = total cash costs (operating cash costs + royalties)

C3 = total costs ( total cash costs + depreciation + amortisation)

There is a "new" concept called "all-in sustaining cash cost" but it is a bit confusing.