There are two versions of the model: -The one rendered by default (called Endogenous), with endogenous price that affects the demands according to the price elasticity slider. Reflecting how reactive are the nodes demand wrt price -With fix price (called Fixed): that in the oil market doesn't apply, but it's an interesting baseline to consider oil purely as flow. And as a modeling tool, this allows the model to capture small supply chains that don't have price setting power.