Informatica Best Practices (Mapping Description)

It is a good practice to note down the name of the developer, Date of development and a brief description of the functionality of the mapping in the description field of the mapping. Whenever there is a change in the mapping the change, date of change and person responsible for change should be noted there. This helps in tracking history of changes in a mapping and acts as a log.
Similarly all major expressions should have a brief description and its functionality, for example a lookup transformation should have the lookup override condition or Source Qualifier should have the filter condition.