The beginning of the amazing events at Krakatoa in 1883 date to May 20 when there were initial rumblings and venting from the volcano, which had been dormant for about 200 years.
A refinery margin is the revenue associated with refining petroleum, expressed as a value per volume (e.g. $/L), net of the cost of the crude oil input. The simplest refining
Operating margin indicates what proportion of a company's revenue (income) remains after variable production costs are paid, such as workers' wages and raw materials. If your company makes a product that costs $10 to produce and it sells for $15, the operating margin is $5. The difference between operating margin and gross manufacturing margin is that the operating margin presents a picture of how much your business makes on every dollar of sale before tax and interest.