About calculatin logic of amount in local currency (MSEG-DMBTR)

HI,Experts,

I want to know calculation logic of amount in local currency (MSEG-DMBTR).

Example:

I create one material docment (movement type is 601).

So I guess the calculation is as below:

Amount in local currency (MSEG-DMBTR) = Quantity(MSEG-MENGE) * Standard price(MBEW-STPRS)

But in face I find it is incorrect.

Could you help me?

Best Regards,

Colin.