It’s often the case that we need to map various attributes on entities into other entities. For example you might need to migrate data from one system to another and structurally the same concepts are held slightly differently. Documenting these mappings is not obvious in the UML, so below I’ve provided a simple example of how a composite structure diagram could be used to provide the mappings. Some notes have been added where conversions need to be performed and these could be represented more formally using diagram references to behavioural diagrams such as sequence or activity diagrams. This is quite possibly not 100% UML compliant / intended usage; but it provides a tool for this type of mapping which otherwise seems to be lacking in the standard UML specification.