Final answer:
The general guideline is to treat as traceable only those costs that would continue over time if the segment was discontinued. Sunk costs, which are costs that have already been incurred and cannot be recovered, should be disregarded in making current decisions.
Step-by-step explanation:
The subject of this question is related to Business. The guideline being referred to is cost analysis and decision making.
When a segment is discontinued, only the costs that would continue to be incurred over time should be treated as traceable. These costs are called avoidable costs because they can be avoided by discontinuing the segment. An example of an avoidable cost would be the salary of an employee assigned specifically to that segment.
On the other hand, sunk costs - costs that have already been incurred and cannot be recovered - should be disregarded in making current decisions. These costs are irrelevant to the decision-making process. An example of a sunk cost would be the initial investment in equipment for the segment.