Yes, but its a cash based P/E which is the key to actually...

Yes, but its a cash based P/E which is the key to actually valuing stocks properely. You basically replace accounting depreciation which is not a real cost, with the amount they spend on sustaining cap ex long run , which is a real cost, and you have the cash flow based P/E.

So when its 4, it means the business is generating 25% of its equity value in cash per year. If that makes sense?
The reason this is really important with mining stocks and infrastructure stock, especially if done a lot of cap ex, tehy will then show large depreciation, as they want to minimise tax. But if the sustaining cap ex runs a lot lower, then they are generating a lot of cash, in spite of the accounting based P/E not showing it.

So for example, with Mins, let suppose they spent $4 bn on it, aand then can depreciate it over 4 years at $1 bn a year, and once built the sustaining cap ex is only $100 m a year.
Let suppose it produces $1 bn of revenue and no costs (just to make really simple). Then with a standard PE it will show no earnings, $1 bn of revenue and $1 bn of depn, but it is in fact generating $900 m of free cash each year, once its up and running. Which is what the euqity shareholders care about as that is what they get to keep in their wallets.
Its also why the analyst models will show higher P/Es for mins, than me, as they calculate using depn rather than sustaining cap ex.