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.
Bat Roosts. The place a bat lives is called its roost. Bats need different roosting conditions at different times of the year and they will often move around to find a roost that meets their needs. Some bats prefer hollow trees, some like caves and some use both at different times.