What does the term "class specific defect" refer to?

The term "class specific defect" refers to a defect that applies only to certain classifications of trains rather than affecting all trains universally. This means that the defect is relevant to specific designs, operational standards, or functionalities of particular types of trains. Understanding the context of train classifications is crucial because it helps in assessing and addressing maintenance or operational issues more effectively by narrowing down the problem to specific train types. This focus allows for targeted troubleshooting and repair efforts rather than a broad approach that may not address the issue accurately. The other options either imply a broader scope that wouldn't fit the definition or do not define the specific criteria of being "class specific."