Allocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.llocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.
Definition of roost. 1  1a : a support on which birds restb : a place where winged animals and especially birds customarily roost. 2  2 : a group of birds roosting together.
Nesting and Roosting Sites. 1  Nesting and roosting sites are protected from the elements and are situated on houses, barns, stadiums, and grain elevators, as well as bridges, wharfs, and cliffs.  Nests in continual use become solid with droppings, feathers, and other debris.