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.
Duncraftâs new series of roosting boxes are different from the standard wooden roosting box for a number of reasons. First, they let birds perch on an interior ladder system. Most roosting boxes have fixed wooden perches, so cleaning the perches and the inside of the box can be difficult.