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.
Roosting boxes are roofed, hollow boxes outfitted with pegged perches along their interior walls. Unlike birdhouses, which accommodate a nest, these boxes are only intended to provide shelter from severe weather for cavity-nesting songbirds.