For example, a mapping in Folder A contains a shortcut to an Expression transformation in Folder B. In Folder B, you update the Expression transformation in a way that causes invalidation. The Repository Service marks the parent mappings in Folder B that use the Expression transformation. The Repository Service also marks the mappings in Folder A that use the shortcut to the Expression transformation with a warning. When you run a session that uses the impacted mappings, the Integration Service validates the mappings. If the mappings are valid, the Integration Service runs the session. If the mappings are invalid, the Integration Service marks the session as invalid and it does not run the session.