A business reports its own office stationary on the balance sheet at $$400$ cost$,$ although it cannot be sold for more than $$10$ as scrap paper. Which accounting principle and$/$or assumption justifies the treatment?

A business reports its own office stationary on the balance sheet at $$400$ cost$,$ although it cannot be sold for more than $$10$ as scrap paper. Which accounting principle and$/$or assumption justifies the treatment? Please answer, will give thumbs up$.$