As you are aware, sources and targets are reusable components, that is, you work on sources in Source Analyzer and targets in Target Designer respectively. Also, you must be aware that you cannot edit sources and targets in Mapping Designer; they can only be edited in Source Analyzer and Target Designer respectively.
Sources and targets are called reusable components because you can use the same source and target in multiple mappings. We can reuse the source or target across multiple mappings only if the metadata requirements of both mappings is exactly the same. Metadata, in this case, means the number of columns, their data type, their data size, indexes, constraints, and so on. Even if there are small changes, you cannot reuse the components.
On the same lines, if we have the same logic to implement across multiple mappings, we can use the reusable transformations, which allow us to reuse the same transformation across mappings. You can only reuse...